Aerodynamic drag reducing apparatus

ABSTRACT

A drag reducing apparatus is provided for use with vehicles having surfaces that are not streamlined. The apparatus includes an exterior cover that forms a drag reducing shape when the apparatus is fully extended. The apparatus can be retracted to a space saving configuration. A scissors linkage extends and retracts the apparatus. The scissors linkage can be motorized, and the motor can extend the scissors linkage by turning in a first direction and can retract the apparatus by turning in a second direction. The scissors linkage can hold the exterior cover taut when the apparatus is fully extended. The scissors linkage can support the exterior cover at intermediate locations when the apparatus is not fully extended. The apparatus can include support linkages and intermediate moveable members that support the exterior cover and define the drag reducing shape.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/980,044,filed Dec. 28, 2010, which is a continuation of application Ser. No.12/390,499, filed Feb. 23, 2009, now U.S. Pat. No. 7,857,376, whichclaims the benefit of U.S. Provisional Patent Application Ser. No.61/029,922, filed Feb. 21, 2008.

This application is related to U.S. patent application Ser. No.12/134,348, filed Jun. 6, 2008, now U.S. Patent Application PublicationNo. 2008/0303310, which claims the benefit of U.S. Provisional PatentApplication Ser. Nos. 60/942,457, filed Jun. 6, 2007, and 61/029,922,filed Feb. 21, 2008; this application is related to U.S. patentapplication Ser. No. 11/837,228, filed Aug. 10, 2007, now U.S. PatentApplication Publication No. 2008/0184835, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/822,058, filed Aug. 10,2006; this application is related to U.S. patent application Ser. No.12/045,022, filed Mar. 9, 2008, now U.S. Patent Application PublicationNo. 2008/0164722, which is a continuation in part of U.S. patentapplication Ser. No. 11/565,254, filed Nov. 30, 2006, now U.S. Pat. No.7,374,230, issued on May 20, 2008, which claims the benefit of U.S.Provisional Patent Application Ser. No. 60/741,155, filed Dec. 1, 2005;and, this application is related to U.S. patent application Ser. No.12/132,585, filed Jun. 3, 2008, which is a continuation of U.S. patentapplication Ser. No. 11/425,854, filed Jun. 22, 2006, now U.S. Pat. No.7,380,868, issued on Jun. 3, 2008, which claims the benefit of U.S.Provisional Patent Application Ser. Nos. 60/694,865, filed Jun. 29,2005, 60/705,026, filed Aug. 2, 2005, and 60/705,029, filed Aug. 3,2005; which patents and applications are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to aerodynamic drag reducing devices foruse with vehicles.

BACKGROUND

Certain vehicles have downstream surfaces, at or near the vehicle'srear, that are not streamlined. Examples include: over-the-road trucksand truck trailers, vans and minivans, motor homes and travel trailers,and pickup trucks. In vehicles such as pickup trucks, onenon-streamlined surface is near the vehicle's center. Certain vehicles,such as semi-trailer trucks, have gaps between otherwise streamlinableexterior surfaces along the vehicle's length. In the case of thesemi-trailer truck, a gap is typically present between a tractor unitand a semi-trailer. Certain of the above vehicles also include reardoors or tail gates.

It is known that a significant amount of aerodynamic drag is createdwhen a vehicle travels at velocities typical on a modern roadway. Thisis due, in large part, to areas of low pressure that are induced onrearward surfaces of the vehicle. The low pressure becomes morepronounced as airflow over the vehicle separates from the rearwardsurfaces of the vehicle. The phenomenon of airflow separation is alsoknown in aircraft wing design and, in this case, causes the wing tostall.

Moving vehicles having blunt rear ends and surfaces facing mainlyrearward are especially affected by airflow separation starting at anabrupt transition between side, top, and bottom surfaces and the nearvertical rearward facing surfaces. The low pressure that the airflowseparation induces is compounded by a relatively large area on which thelow air pressure acts in comparison with more streamlined vehicles.

Moving vehicles having an interruption in otherwise streamlined, nearstreamlined, or streamlinable exterior surfaces along the length of thevehicle are subjected to increased aerodynamic drag created byturbulence as airflow over the vehicle crosses the interruption.

The low air pressure (partial vacuum) acting on the rear surfaces of amoving vehicle produces a drag force that resists forward motion of thevehicle. Increased turbulence caused by gaps and interruptions inotherwise streamlined or streamlinable exterior surfaces also produces adrag force that resists the forward motion of the vehicle. These dragforces are opposed by the vehicle's engine and require power that istypically produced by burning fuel. Any reduction in aerodynamic dragresults in a reduction in fuel consumption.

In an era of diminishing crude oil reserves, potential limits onatmospheric green house gas emissions in response to global warming, andincreasing environmental consciousness, fuel efficiency improvements area growing concern. Aerodynamic improvements are especially valuablesince they can be combined with other improvements such as engineefficiency and reduced chassis weight. Increased fuel efficiency alsoprovides a valuable benefit of increasing a range a given vehicle cantravel before refueling.

At a given speed, streamline vehicles, such as certain high-speed carsand airplanes, have markedly lower airflow separation and thereforemarkedly lower aerodynamic drag in comparison with vehicles having bluntrear ends. Such streamline vehicles generally have gently taperingreward surfaces designed to keep airflow attached. A similarstreamlining technique has also been applied to over-the-road truckswhere it is known as a “boat-tail”. Boat-tails significantly increasethe length of a vehicle. In addition, they may interfere with convenientaccess to the rear doors of the vehicle. There is a need for a devicethat provides streamlined rear surfaces to the rear of vehicles havingblunt rear ends without introducing unacceptable limitations to thevehicle length or the rear door function. There is also a need to bridgegaps across discontinuities along the length of vehicles, such as thegap between the tractor unit and the semi-trailer of the semi-trailertruck. The present disclosure satisfies these and other needs.

SUMMARY

The present disclosure is concerned with providing an aerodynamic dragreducing apparatus for vehicles for the purpose of reducing energyconsumption and related tailpipe emissions. The principles of thepresent disclosure can also be applied to a hydrodynamic drag reducingapparatus. More specifically, in certain embodiments, this is achievedby adding gently sloping surfaces downstream of rearward facing surfacesof the vehicle with a goal of reducing airflow separation andaerodynamic drag. More specifically, in other embodiments, this isachieved by filling gaps and/or discontinuities along a length of thevehicle. The gap and/or the discontinuity may vary and open and closewhile the vehicle is in operation. Both of these techniques, usedseparately or together, reduce fuel consumption of the vehicle.

When the concepts of the present disclosure are employed to add atapering rear surface(s) to a vehicle, means are included to retract andextend the tapering rear surface(s) when needed for various purposes. Inaddition, certain embodiments of the present disclosure may be mountedon or integrated with one or more rear doors of a vehicle therebyallowing access to the rear of the vehicle. Alternatively, otherembodiments of the present disclosure may include means for moving thedrag reducing apparatus to allow access to the rear of the vehicle.

When the concepts of the present disclosure are employed to add fillsurfaces that fill gaps and/or discontinuities along the length of thevehicle, means are included to lengthen and shorten the fill surfaces asneeded. For example, a gap typically exists between a tractor unit and asemi-trailer of a semi-trailer truck while heading straight down a levelroad. Portions of the gap expand and contract as the semi-trailer truckencounters bumps and other slope changes on the road. In addition, whenthe semi-trailer truck executes a turn and certain parking maneuvers, aportion of the gap on one side of the semi-trailer truck can greatlyexpand while a portion of the gap on the opposite side greatlycontracts. In certain embodiments, a main purpose of the fill surfacesare to fill the gap between the tractor unit and the semi-trailer of thesemi-trailer truck while heading approximately straight down a road withan approximately uniform slope. This condition exists for a large shareof driving time under many normal driving routines, especially at highspeeds, and is where aerodynamic benefits are most valuable. Under otherdriving conditions, especially at low speeds while executing sharpturns, portions of the gap may expand beyond the reach of the fillsurfaces creating a gap between the fill surfaces and the semi-traileror the tractor unit. The fill surfaces of the present disclosure can berefracted from an extended configuration to match the contracted portionof the gap. The fill surfaces can be fully retracted to a retractedconfiguration at low speeds and/or when certain maneuvers (e.g., sharpturns) are executed.

On certain vehicles, simply adding the required gently sloping surfacesto the rear of the vehicle would result in a substantial increase invehicle length. This length increase would be acceptable, in many cases,on the open road in uncongested traffic, but would be impractical oncrowded urban roadways, in parking lots, in campgrounds, and by loadingdocks. To address this, certain embodiments of the present disclosurehave two primary configurations. The first is an extended configurationthat reduces drag and fuel consumption, especially at highway speeds.The second is a retracted configuration that provides much less, if any,drag reduction but results in a more compact vehicle that is practicalin crowded areas. This combination of configurations in the sameapparatus is especially useful since zones of higher speed traffic areoften not congested. These high-speed zones are also where the dragreducing potential is the highest. Likewise, congested areas often havereduced traffic speed with less drag reducing potential, but in thesecases, the retracted configuration may be required for maneuvering.

In order to easily and conveniently transform the drag reducingapparatus between the retracted configuration and the extendedconfiguration, one or more flexible sheet-like exterior covers are heldbetween a first end and a second end. The first end of the exteriorcover can be directly or indirectly attached to the vehicle, and thesecond end of the exterior cover can be attached to a moveable endmember (e.g., a moveable end frame). The exterior cover can be mediallyattached to one or more moveable intermediate members. The moveableintermediate members can take the form of a frame, a hoop, a supportpiece, a panel, a rod, a tube, a strap, a holder, etc. In embodimentsusing moveable intermediate members, a first moveable intermediatemember (or first set of moveable intermediate members) is supported fromthe vehicle by a first set of linkages (e.g., a support linkage and/or adriving linkage) providing support and/or position control for the firstmoveable intermediate member. Additional moveable intermediate memberscan be used and can be held by additional sets of links and/or linkages.Each additional set of links and/or linkages can connect itscorresponding moveable intermediate member to the moveable intermediatemember preceding it. The moveable end member can be similarlysupported/held/connected by an additional set of links and/or linkagesto the moveable intermediate member preceding it. In embodiments notusing moveable intermediate members, the moveable end member is directlyor indirectly connected to the vehicle by the set of linkages (e.g., thesupport linkage and/or the driving linkage). In certain embodiments, thefirst end of the exterior cover is held in a hoop shaped configurationby the vehicle or a member attached to the vehicle. In certainembodiments, the second end of the exterior cover is held in a hoopshaped configuration by the moveable end member attached to the secondend of the exterior cover.

The moveable end member can be extended and/or retracted by the drivinglinkage (e.g. a scissors linkage). The moveable end member can bevertically supported by support linkages (e.g. bi-fold linkages). Inembodiments using one or more moveable intermediate members, themoveable intermediate members can be extended and/or retracted by thedriving linkage (e.g. the scissors linkage) and can be verticallysupported by support linkages (e.g. the bi-fold linkages).

The moveable members (i.e., the moveable end member and, if used, themoveable intermediate members) can be extended, retracted, andvertically supported by the driving linkage in combination with atension member. By arranging the driving linkage to support compressiveloads and the tension member to support tensile loads, a triangularstructure (i.e., a load carrying triangle) can be formed with thedriving linkage forming a first side of the triangle, the tension memberforming a second side of the triangle, and either the vehicle or anattachment member attached to the vehicle forming a third side of thetriangle. By changing lengths of the tension member, the drivinglinkage, or both the tension member and the driving linkage, the loadcarrying triangle's shape is changed and can thereby extend and retractthe apparatus. For example, by lengthening both the driving linkage andthe tension member, the apparatus can be extended, and by shorteningboth the driving linkage and the tension member, the apparatus can beretracted. To arrange the driving linkage to support compressive loads,the driving linkage is preferably pivotally attached to the vehicle orthe attachment member attached to the vehicle. In the extendedconfiguration of the apparatus, the driving linkage extends rearward andpreferably upward behind the vehicle. To arrange the tension member tosupport tensile loads, the tensile member is preferably attached to thevehicle or the attachment member attached to the vehicle and oppositelyattached to the driving linkage. In the extended configuration of theapparatus, the tension member extends rearward and preferably downwardbehind the vehicle. The net load acting on the apparatus has apredominantly downward vertical component and thus causes compression inthe driving linkage and tension in the tension member.

As the apparatus is extended and retracted and the load carryingtriangle's shape changes, tensile loads are typically carried by thetension member and compressive loads are typically carried by thedriving linkage. When the apparatus is fully extended, a portion orsubstantially all of the tensile loads can be transferred from thetension member to the exterior cover, and additional compressive loadscan be generated by the driving linkage to apply additional tension tothe exterior cover to keep the exterior cover taut. When the apparatusis fully retracted and/or nearly fully retracted, the load carryingtriangle's shape can become flat or substantially flat and the apparatuscan be substantially supported by tensile loads within the tensionmember. In such a flat or substantially flat configuration, compressiveloads within the driving linkage can become negligible.

Means for limiting the motion of each moveable member can be provided.The motion of each moveable member is preferably limited to positionsbetween its extended configuration position and its retractedconfiguration position. In certain embodiments, the support links and/orsupport linkages have joint stops for this purpose. In certainembodiments, one or more tensile load carrying members, such as a cord,a strap, or a chain, are attached to the moveable members and becometaut when the moveable member has reached its extended configurationposition. In certain embodiments, the exterior cover serves as thetensile load carrying member for this purpose. In certain embodiments,the driving linkage limits the motion of each moveable member or some ofthe moveable members.

Means for biasing the drag reducing apparatus to move toward either theextended configuration and/or the retracted configuration can beprovided. In certain embodiments, the linkage (e.g., the supportlinkages and/or the driving linkage) can have one or more joints thatare spring loaded for this purpose. This can include bi-stable joints(e.g., a joint with two detents) to move away from a central positionand toward the extended configuration when near the extendedconfiguration and toward the retracted configuration when near theretracted configuration. In other embodiments, the support linkageand/or the driving linkage can have flexible, spring elements thatreplace one or more joints. The spring elements can also bias thelinkage in one or both directions.

In certain embodiments, gravity can be used to bias the apparatus tomove toward the extended configuration, the retracted configuration, orboth the extended and the retracted configurations. Such gravity biasedembodiments typically have a center-of-gravity that is higher when theapparatus is between the extended and the retracted configurations at anintermediate configuration. Preferably, the center-of-gravity of theapparatus becomes continuously lower as the apparatus moves from theintermediate configuration to the fully extended configuration, and thecenter-of-gravity becomes continuously lower as the apparatus moves fromthe intermediate configuration to the fully retracted configuration.

Means for automatically extending and retracting the drag reducingapparatus can be provided. In certain embodiments, a retractiontension-member (e.g., a chain, a cable, a belt, a rope, a cord, etc.) isattached to an end moveable member and is reeled in by a pulley poweredby a motor. In addition, the support linkages and/or the driving linkageare biased to extend the apparatus as mentioned in the precedingparagraph. Thus, operating the motor in a first direction overpowers thesupport linkage and/or driving linkage bias and retracts the apparatuswhile operating the motor in a second, opposite direction feeds theretraction tension-member outward and allows the biased (e.g.,spring-loaded) support linkages and/or driving linkage to extend theapparatus.

In certain embodiments, the driving linkage is a scissors linkage, andthe tension-member can be routed through the scissors linkage and pullvertices of the scissors linkage together. By pulling the vertices ofthe scissors linkage together, the scissors linkage expands (i.e.,lengthens) and can extend the drag reducing apparatus. The sametension-member can both pull the vertices of the scissors linkage,causing extension, and retract (i.e., compress) the scissors linkage.The routing of the tension-member can be such that moving thetension-member in a first direction expands the scissors linkage andthus the apparatus, and moving the tension-member in a second directionretracts the scissors linkage and thus the apparatus.

In embodiments filling a gap, bearing loads from across the gap canretract the extension biased apparatus. In this case, movement of thevehicle causing at least a portion of the gap to become smaller cancause portions of the vehicle to bear against the apparatus andoverpower the extension bias thus causing the apparatus to retract(e.g., a corner of the semi-trailer can reduce the gap and bear againstthe apparatus during a sharp turn causing it to retract). In this case,the extension bias returns the apparatus to the extended configurationas the gap expands (e.g., upon returning to a straight course, thecorner of the semi-trailer restores the gap and the extension biasextends the apparatus). Outwardly biasing the support linkage and/ordriving linkage is one method of outwardly biasing the apparatus. Othermethods include pressurized air within the apparatus, an extensionspring between the apparatus' ends, and combinations of these and othermethods.

In an alternative embodiment, the scissors linkage is biased to retractthe apparatus which can be extended by partial vacuum created by vehiclemovement operating on the exterior covers. In addition to or separatelyfrom the partial vacuum, a positive pressure can be created within theapparatus by a forward opening into oncoming airflow. The forwardopening converts dynamic pressure of the oncoming airflow into staticpressure within the apparatus, thus extending the apparatus. In anotheralternative embodiment, the retraction biased apparatus is extended bycompressed air fed within the apparatus. In embodiments filling a gap,tension members (e.g., cables and/or stretchable cords) can extend theretraction biased apparatus. In this case, the tension members pull toextend the apparatus from across the gap and may be tensioned by amotor, cable tensioning springs, the stretchable cord itself, or othermeans.

In certain embodiments, the driving linkage (e.g., a scissor linkage) isprovided to extend and/or retract the apparatus. The example scissorlinkage may be actuated by an actuator that causes the scissor linkageto extend and retract, thus extending and retracting the apparatus. Theactuator may include a drive that directly moves certain points of thescissor linkage. Such a drive may include a screw and nut assembly.Other such drives may include a belt and pulley arrangement. The scissorlinkage may be extended by routing a tension-member (e.g., a cable, abelt, a chain, etc.) between various joints and/or points of the scissorlinkage. A motor may retract the tension-member, drawing certain of thejoints and/or points together thus extending the scissor linkage. Inembodiments where a tension-member extends the scissor linkage, the sametension-member or another tension-member may retract the apparatus bypulling part of the apparatus toward the retracted configuration. Toaccommodate vehicles where access to the rear end is required, certainembodiments of the present disclosure allow the apparatus to betemporarily moved without removal from the vehicle. In certainembodiments, a single whole apparatus is mounted on a support panel,door, framework, etc. that in turn is mounted on a hinge, linkage,linear slide, etc. Other embodiments have the overall drag-reducingshape split into two halves. These halves can be mounted on hinges andopened, providing access to the rear of the vehicle. Optionally, thehalves can be integrated with the rear doors of the vehicle.

In certain embodiments, the drag reducing apparatus can be stored inpart or in whole underneath a cargo carrying area of a trailer. Thedriving linkages and/or support linkages can be mounted underneath thecargo carrying area and extend outwardly when the drag reducingapparatus is moved from the retracted to the extended configuration. Theapparatus can be supported by a frame that is rotatably attached to thetrailer. By swinging the frame, the apparatus can be stored underneaththe cargo carrying area. The apparatus can be swung to the side of thetrailer or can tuck under the rear end of the trailer.

The scissors linkage can take various forms including a ladderconfiguration wherein pairs of links of the scissors linkage are heldtogether by cross-members that resemble rungs on a ladder. The links ofthe scissors linkage can take various forms including a form having acrank-like configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

The benefits and advantages of the present disclosure will become morereadily apparent to those of ordinary skill in the relevant art afterreviewing the following detailed description and accompanying drawings,wherein:

FIGS. 1 through 70 illustrate aerodynamic drag reducing apparatusesadapted for use behind a sports-utility vehicle including variousscissors linkages. In particular:

FIGS. 1 through 4 illustrate the apparatuses of FIG. 1 in a fullyextended configuration mounted behind the sports-utility vehicletogether with an adapter fairing. In particular:

FIG. 1 is a rear right perspective view.

FIG. 2 is a right side elevation view.

FIG. 3 is a partial top plan view.

FIG. 4 is a rear elevation view.

FIGS. 5 through 24 illustrate a first apparatus of FIG. 1, removed fromthe sports-utility vehicle, including a scissors linkage actuated by abelt driven rail-cam follower mechanism. In particular:

FIGS. 5 through 9 illustrate the first apparatus of FIG. 5 in the fullyextended configuration. In particular:

FIG. 5 is a front left perspective view.

FIGS. 6 through 9 illustrate the apparatus of FIG. 5 with an exteriorcover removed for viewing clarity. In particular:

FIG. 6 is a right rear perspective view.

FIG. 7 is a right side elevation view.

FIG. 8 is a top plan view.

FIG. 9 is a front plan view.

FIGS. 10 through 13 illustrate the first apparatus of FIG. 5 in apartially extended configuration with the exterior cover removed forviewing clarity. In particular:

FIG. 10 is a right rear perspective view.

FIG. 11 is a right side elevation view.

FIG. 12 is a top plan view.

FIG. 13 is a front plan view.

FIGS. 14 through 17 illustrate the first apparatus of FIG. 5 in a fullyretracted configuration with the exterior cover removed for viewingclarity. In particular:

FIG. 14 is a right rear perspective view.

FIG. 15 is a right side elevation view.

FIG. 16 is a top plan view.

FIG. 17 is a front plan view.

FIGS. 18 through 24 illustrate the first apparatus of FIG. 5 with aright support linkage, the exterior cover, and portions of all but afirst hoop frame removed for viewing clarity. In particular:

FIGS. 18 and 19 are right rear perspective views. In particular:

FIG. 18 is with the apparatus in the fully extended configuration.

FIG. 19 is with the apparatus in the partially extended configuration.

FIGS. 20 and 21 are with the apparatus in the partially extendedconfiguration. In particular:

FIG. 20 is a right side elevation view.

FIG. 21 is a partial top plan view.

FIG. 22 through 24 are with the apparatus in the fully retractedconfiguration. In particular:

FIG. 22 is a right rear perspective view.

FIG. 23 is a right side elevation view.

FIG. 24 is a top plan view.

FIGS. 25 through 30 illustrate a second apparatus of FIG. 1, removedfrom the sports-utility vehicle with the right support linkage, theexterior cover, and the portions of the hoop frames removed for viewingclarity, including a scissors linkage actuated by a screw drivemechanism. In particular:

FIGS. 25 and 26 illustrate the second apparatus of FIG. 25 in the fullyextended configuration. In particular:

FIG. 25 is a right rear perspective view.

FIG. 26 is a right side elevation view.

FIGS. 27 and 28 illustrate the second apparatus of FIG. 25 in thepartially extended configuration. In particular:

FIG. 27 is a right rear perspective view.

FIG. 28 is a right side elevation view.

FIGS. 29 and 30 illustrate the second apparatus of FIG. 25 in the fullyretracted configuration. In particular:

FIG. 29 is a right rear perspective view.

FIG. 30 is a right side elevation view.

FIGS. 31 through 42 alternate between a third apparatus of FIG. 1 and anisolated tension-member of the figure immediately preceding it (e.g.,FIG. 32 illustrates the tension-member of FIG. 31 in isolation). Theincluded odd numbered figures illustrate the third apparatus of FIG. 31,removed from the sports-utility vehicle with the right support linkage,the exterior cover, and the portions of the hoop frames removed forviewing clarity, including a scissors linkage actuated by atension-member drive. In particular:

FIGS. 31 through 34 illustrate the third apparatus of FIG. 31 in thefully extended configuration. In particular:

FIGS. 31 and 32 are rear right perspective views.

FIGS. 33 and 34 are right rear perspective views.

FIGS. 35 through 38 illustrate the third apparatus of FIG. 31 in thepartially extended configuration. In particular:

FIGS. 35 and 36 are rear right perspective views.

FIGS. 37 and 38 are right rear perspective views.

FIGS. 39 through 42 illustrate the third apparatus of FIG. 31 in thefully retracted configuration. In particular:

FIGS. 39 and 40 are rear right perspective views.

FIGS. 41 and 42 are right rear perspective views.

FIGS. 43 and 44 show the hoop frames of FIG. 18 nested within eachother.

FIGS. 45 and 46 illustrate a partial cross-section of one of the hoopframes of FIG. 18. In particular:

FIG. 45 is a non-exploded view.

FIG. 46 is an exploded view.

FIGS. 47 through 52 alternate between a fourth apparatus of FIG. 1, inthe fully extended configuration, and an isolated tension-member of thefigure immediately preceding it (e.g., FIG. 48 illustrates thetension-member of FIG. 47 in isolation). The included odd numberedfigures illustrate the fourth apparatus of FIG. 47, removed from thesports-utility vehicle with the exterior cover in phantom line forviewing clarity, including a scissors linkage actuated by atension-member drive. In particular:

FIGS. 47 and 48 are right rear perspective views.

FIGS. 49 and 50 are left front underside perspective views.

FIGS. 51 and 52 are right side cross-sectional elevation views.

FIG. 53 is a partial right rear cross-sectional view of the fourthapparatus of FIG. 47 in the fully extended configuration, removed fromthe sports-utility vehicle, and with the exterior cover in phantom linefor viewing clarity.

FIGS. 54 through 63 are cross-sectional views that alternate between thefourth apparatus of FIG. 47 and an isolated tension-member of the figureimmediately preceding it (e.g., FIG. 55 illustrates the tension-memberof FIG. 54 in isolation). The included even numbered figures illustratethe fourth apparatus of FIG. 47, removed from the sports-utility vehiclewith the exterior cover removed for viewing clarity. In particular:

FIGS. 54 and 55 are right rear perspective views with the apparatus in apartially extended configuration.

FIGS. 56 and 57 are right side elevation views with the apparatus in apartially extended configuration.

FIGS. 58 through 61 are right rear perspective views. In particular:

FIGS. 58 and 59 are with the apparatus in a near-retractedconfiguration.

FIGS. 60 and 61 are with the apparatus in the fully retractedconfiguration.

FIGS. 62 and 63 are right side elevation views with the apparatus in thefully retracted configuration.

FIG. 64 is a partial right side cross-sectional elevation viewillustrating a boost cam and a boost cam follower overlaid with a camlink and a pivot bracket in the configuration of FIG. 62.

FIG. 65 is a right rear cross-sectional perspective view of a fifthapparatus of FIG. 1 in the fully extended configuration, removed fromthe sports-utility vehicle, with the exterior cover in phantom line forviewing clarity, and including the scissors linkage of FIG. 47 actuatedby another tension-member drive.

FIG. 66 is a right rear perspective view of a tension-member of FIG. 65in isolation.

FIGS. 67 through 70 are views of the fourth apparatus of FIG. 47 in thepartially extended configuration with the exterior cover and portions ofan attachment member removed for viewing clarity. In particular:

FIG. 67 is a left rear perspective view.

FIG. 68 is an enlarged partial view of a portion of FIG. 67 illustratinga portion of a joint of the scissors linkage.

FIG. 69 is a cross-sectional view from above through the joint of FIG.68.

FIG. 70 is an enlarged partial view of a portion of FIG. 69 illustratingthe portion of the joint of FIG. 68.

FIGS. 71 through 96 illustrate aerodynamic drag reducing apparatuses,including scissors linkages, adapted for use across gaps in and behind asemi-trailer truck. In particular:

FIGS. 71 and 72 illustrate the apparatuses of FIG. 71 in fully extendedconfigurations. A rear-mounted apparatus is mounted behind a trailer ofthe semi-trailer truck, and a gap filling apparatus is mounted between atractor and the trailer of the semi-trailer truck. In particular:

FIG. 71 is a left front perspective view.

FIG. 72 is a right rear perspective view.

FIGS. 73 through 78 illustrate the rear-mounted apparatus of FIG. 71 inthe fully extended configuration. In particular:

FIGS. 73 through 75 show the apparatus removed from the trailer of FIG.71. In particular:

FIG. 73 is a front right perspective view with right and left scissorslinkages visible within an exterior cover.

FIGS. 74 and 75 are partial perspective views with the right scissorslinkage and the exterior cover removed for clarity. In particular:

FIG. 74 is a view from the front right.

FIG. 75 is a view from the right front with an end panel of theapparatus cut-away.

FIGS. 76 through 78 are partial views showing the apparatus attached tothe trailer of FIG. 71 with the exterior cover shown in phantom line forviewing clarity. In particular:

FIG. 76 is a left rear perspective view.

FIG. 77 is a cross-sectional left elevation view.

FIG. 78 is a left elevation view.

FIGS. 79 through 87 are partial views illustrating the rear-mountedapparatus of FIG. 71, with the exterior cover removed for viewingclarity, attached to the trailer. In particular:

FIGS. 79 through 81 show the apparatus in a partially extendedconfiguration. In particular:

FIG. 79 is a left rear perspective view.

FIG. 80 is a cross-sectional left elevation view.

FIG. 81 is a left elevation view.

FIGS. 82 through 84 show the apparatus in a fully retractedconfiguration. In particular:

FIG. 82 is a left rear perspective view.

FIG. 83 is a left elevation view.

FIG. 84 is a cross-sectional left elevation view.

FIGS. 85 through 87 show the apparatus in a configuration allowingaccess to the trailer's rear end. In particular:

FIG. 85 is a left rear perspective view.

FIG. 86 is a rear elevation view.

FIG. 87 is a cross-sectional rear elevation view.

FIGS. 88 through 90 are perspective views illustrating the left scissorslinkage of FIG. 73 in the partially extended configuration of FIG. 79.In particular:

FIGS. 88 and 89 are views from the left rear. In particular:

FIG. 88 shows scissor links including a link body and a drive andscissor links including a crank.

FIG. 89 shows the drives and shows the scissor links including the crankof FIG. 88 but removes the link body of the scissor links including thedrive for viewing clarity.

FIG. 90 is an exploded view from the rear left.

FIG. 91 is a perspective view of the scissor link including the crank ofFIG. 88.

FIG. 92 is a perspective view of the link body of FIG. 88.

FIG. 93 is a perspective view of the drive of FIG. 88.

FIG. 94 is a rear left perspective view of another drag reducingapparatus of FIG. 71 wherein the right and left scissors linkages foldflat.

FIG. 95 is a left side cross-sectional elevation view of the dragreducing apparatus of FIG. 94.

FIG. 96 is a perspective view of the left scissors linkage of FIG. 94shown folded flat.

DETAILED DESCRIPTION

While the present disclosure is susceptible of embodiment in variousforms, there are shown in the drawings and will hereinafter be describedpresently preferred embodiments with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentsillustrated.

The embodiments presented are also shown in various forms and shapes andwith various optional features. These variations also areexemplifications of the disclosure and are not intended to limit thecombinations of forms, shapes, and optional features.

In the present disclosure, the term “vehicle” or “vehicles” can broadlyrefer to vehicles, trailers, aircraft, water craft, and other bodiesthat have relative movement with a fluid and are subject to aerodynamicand/or hydrodynamic drag.

The aerodynamic performance and efficiency of certain over-the-roadvehicles can be significantly improved by adding streamlining surfacesto the vehicle's rear. In particular, vehicles with blunt rear ends,such as certain trucks, trailers 101, and sports-utility-vehicles 201have potential for improved aerodynamics. Adding an aerodynamic dragreducing apparatus 102 behind the trailer 101 of a semi-trailer truck100 will reduce aerodynamic drag and improve aerodynamic performance(see FIGS. 71 and 72). Adding an aerodynamic drag reducing apparatus 202or 302 behind the sports-utility vehicle 201 will reduce aerodynamicdrag and improve aerodynamic performance (see FIGS. 1-4).

The aerodynamic performance and efficiency of certain vehicles can besignificantly improved by filling gaps along the vehicle's length. Forexample, vehicles with trailers, such as the semi-trailer truck 100typically have a gap G present between a tractor unit 110 and thesemi-trailer 101. Filling the gap G with relatively smooth streamliningsurfaces, such as a gap filling aerodynamic drag reducing apparatus 105,will reduce aerodynamic turbulence and improve aerodynamic performanceof the semi-trailer truck 100 (see FIGS. 71 and 72).

Certain vehicles, such as the typical semi-trailer truck 100, canbenefit both from adding streamlining surfaces to the rear of thevehicle (e.g., the aerodynamic drag reducing apparatus 102) and byfilling gaps along the length of the vehicle (e.g. with the gap fillingaerodynamic drag reducing apparatus 105). Certain vehicles, such as thetypical semi-trailer truck 100, can benefit from adding streamliningsurfaces to the rear of the vehicle (e.g., the aerodynamic drag reducingapparatus 102), by filling gaps along the length of the vehicle (e.g.with the gap filling aerodynamic drag reducing apparatus 105), and byadding trailer skirts (e.g., trailer skirts 190R, 190L, 192R, and/or192L) to the trailer 101 (see FIGS. 71 and 72).

The example aerodynamic drag reducing apparatuses 102, 103, 202, 302 ofthe present disclosure are suitable for use behind certain trailers 101and vehicles 201 with vertical or near vertical rearward facingsurfaces. Other aerodynamic/hydrodynamic drag reducing apparatuses basedon the broad principles of the present disclosure can be applied toother vehicles including panel trucks, van trucks, station wagons,trucks without a separable trailer, tanker trucks, tanker trailers,motor homes, busses, sedan deliveries, aircraft, airplanes, helicopters,watercraft, boats, submarines, etc. Other objects, with relative motionto a fluid, can also employ drag reducing apparatuses based on theprinciples of the present disclosure. For example, an anchored buoy canbe fitted with a deployable drag reducing apparatuses as it has watercurrents and wind that move past it from time to time. A windsock canemploy principles of the present disclosure as prevailing winds flowpast the windsock.

The vehicles and other objects to be fitted with drag reducingapparatuses can have a rectangular cross-section, such as thesemi-trailer 101, or can have a non-rectangular cross-section, such asthe tanker trailers and the sports-utility-vehicle 201. The dragreducing apparatuses, including apparatuses 102, 103, 105, 202, 302,serve to streamline the objects, including the vehicles 100, 101, 201,when in an extended configuration as shown at FIGS. 1-4, 71, and 72.When desired, the aerodynamic drag reducing apparatus 102, 103, 105,202, 302 can transform into a retracted configuration to save spaceand/or to provide clearance as shown at FIGS. 14-17, 60, 62, 82-87, 94,and 95. The ability to form two configurations and transform from one tothe other without disassembly is facilitated by one or more moveablemembers 108, 207, 208, 307, 308 (e.g., a moveable panel, frame, hoop,rod, tube, etc.). Each moveable member 108, 207, 208, 307, 308 issupported and/or positioned by one or more sets of linkages 140R, 140L,240, 311, 340, 411. The moveable members 108, 207, 208, 307, 308 supportone or more exterior covers 104, 204, 304. The exterior covers 104, 204,304 preferably provide a gently sloping drag reducing surface when thedrag reducing apparatus 102, 103, 105, 202, 302 is in the extendedconfiguration.

The present disclosure concerns an aerodynamic drag reducing apparatus105 suitable for use with certain vehicles 100 having one or more gaps Galong the vehicle's 100 length (see FIGS. 71 and 72). The aerodynamicdrag reducing apparatus 105 serves to streamline the vehicle 100,especially when the vehicle 100 is in a straight configuration, as shownat FIGS. 71 and 72, by filling the gap G. When the vehicle 100 is not inthe straight configuration, such as when in a turn or starting up aramp, portions of the gap G may become smaller. The apparatus 105accommodates the changing gap G by retracting as needed. Upon thevehicle 100 returning to the straight configuration, the apparatus 105extends and again fills the gap G. The ability to flexibly conform tothe changing gap G is made possible by the use of one or more moveablemembers and linkages, as disclosed in the present disclosure. The one ormore moveable members support one or more exterior covers. The exteriorcover(s) provides a filling surface for the gap G and can also provide atransition between the varying shapes of the tractor unit 110 and thesemi-trailer 101. Preferably, the cover provides a smooth, gentlysloping transition between the tractor unit 110 and the semi-trailer101. The shapes of the tractor unit 110, the semi-trailer 101, and theapparatus 105 can be designed together in an optimized, complementary,and integrated design.

In certain embodiments, illustrated at FIGS. 1-46, an attachment member306 (e.g., an attachment frame, an attachment hoop, fasteners, clips,etc.) joins the drag reducing apparatus 302 to the vehicle 201 byserving as a connection point for the first set of support linkages 311₁, 411 ₁. In addition, the attachment member 306 is connected to orintegrated with the vehicle 201. In an example embodiment, illustratedat FIG. 5, a mounting post 310 can be mounted in a hitch receiver of thevehicle 201 and a set of mounting straps 312 can be mounted to a luggagerack of the vehicle 201. In certain embodiments, a first end of theexterior cover 304 is attached to an adapter fairing 305 placed betweenthe vehicle 201 and the drag reducing apparatus 302. The first end ofthe exterior cover 304 can be attached to the attachment member 306, theadapter fairing 305, or both. The exterior cover 304 can be attached tosome or all of the moveable members 307 ₁₋₄. A second end of theexterior cover 304 can be attached to the moveable end member 308. Inthe present example embodiment, the moveable member 307 ₄ and themoveable end member 308 can be combined and/or attached, and themoveable intermediate members 307 ₁₋₃ are positioned between theattachment member 306 and the moveable end member 308. The drivinglinkage 340 is connected to the attachment member 306 and the moveablemember 307 ₄ that is attached to the moveable end member 308. In certainembodiments, the driving linkage 340 is also connected to the moveableintermediate members 307 ₁₋₃.

In certain embodiments, illustrated at FIGS. 1-4 and 47-70, anattachment member 206 (e.g., an attachment frame, an attachment hoop,fasteners, clips, etc.) joins the drag reducing apparatus 202 to thevehicle 201 by serving as a connection point for the driving linkage240. In addition, the attachment member 206 is connected to orintegrated with the vehicle 201. In an example embodiment, illustratedat FIG. 49, a mounting post 210 can be mounted in a hitch receiver ofthe vehicle 201 and a set of mounting straps 212 can be mounted to aluggage rack of the vehicle 201. In certain embodiments, the exteriorcover 204 is attached to an adapter fairing 305 placed between thevehicle 201 and the drag reducing apparatus 202. The exterior cover 204can be attached to the attachment member 206, the adapter fairing 305,one or more moveable intermediate members 207 ₁₋₅, and/or the moveableend member 208. The exterior cover 204 can be sandwiched and clampedbetween the attachment member 206 and a cover clamp 205. The cover clamp205 can serve as a mounting bracket for the adapter fairing 305. Themoveable intermediate members 207 ₁₋₅ are positioned between theattachment member 206 and the moveable end member 208. The drivinglinkage 240 is connected to the attachment member 206 and the moveablemember 208. The driving linkage 240 is also connected to the moveableintermediate members 207 ₁₋₅. An end mount 247 can connect the scissorslinkage 240 with the moveable end member 208 (see FIG. 62). In theexample drag reducing apparatuses 202 and 302, the attachment members206 and 306 are generally positioned vertically and the adapter fairing305 blends in with non-vertical surfaces near the vehicle's 201rear-end. In other embodiments, similar drag reducing apparatuses candirectly blend in to the vehicle 201 or another vehicle with anon-vertical rear-end. In such embodiments, an exterior cover can beattached directly to the vehicle 201 or another vehicle thus eliminatingthe need for an adapter fairing. The rear-end of the vehicle 201 isnear-vertical and thus the fairing's 305 forward end is alsonear-vertical. In other embodiments, rearward surfaces of a vehicle neednot be near-vertical to blend in with a drag reducing apparatus madeaccording to principles of the present disclosure. The non-near-verticalsurfaces of such vehicles can be blended to such drag reducingapparatuses by an adapter fairing or directly to an exterior cover ofsuch apparatuses.

In certain embodiments, illustrated at FIGS. 71-96, an attachment member106 (e.g., an attachment frame, an attachment hoop, fasteners, clips,etc.) joins the drag reducing apparatus 102, 103 to the vehicle 101(e.g., the trailer 101) by serving as a connection point for the drivinglinkages 140R and 140L. In addition, the attachment member 106 isconnected to or integrated with the vehicle 101. In an exampleembodiment, illustrated at FIGS. 73, 76, and 85, the attachment member106 is configured as an attachment frame with a vertical right member106R, a vertical left member 106L, a horizontal top member 106T, and ahorizontal bottom member 106B. The attachment member 106 can includemounting pins 121. A pair of links 122 can be rotatably connected to aco-axial pair of the mounting pins 121 and to a pair of co-axialmounting pins 124 attached to the trailer 101. The pair of links 122 andthe associated rotatable connections can from a compound hinge thatenables the attachment member 106 to be swung from the rear (see FIG.82) to the side (see FIG. 85) of the trailer 101. A pair of latchinglinks 123 can also be provided to hold the attachment member 106 to thetrailer 101. By swinging the apparatus 102 to the side of the trailer101 at least a portion of the apparatus 102 can be stored underneath atrailer box 120 of the trailer in a stowage area 109 (see FIGS. 86 and87). The stowage area 109 is typically defined by a bottom side 120B ofthe trailer box 120 which bounds the top of the stowage area 109. Thestowage area 109 extends forward to the rearmost wheel of the trailer.

The trailer 101, illustrated at FIGS. 71, 72, and 76-87 includes thetrailer box 120 with a top side 120T, the bottom side 120B, a right side120R, and a left side 120L. At the rear of the trailer 101, a frame 180is typically positioned. The frame 180 typically includes a horizontalmember 184 supported by a right vertical member 182R and a left verticalmember 182L. Such frames 180 often serve as safety devices and engage abumper of a passenger car if the passenger car should collide with therear end of the trailer 101. By engaging the bumper of the car, the caris at least somewhat held from sliding under the bottom side 120B of thetrailer box 120. The frame 180 can be used to support the drag reducingapparatus 102. The frame 180 can directly support the linkages 140R,140L of the apparatus or can support the attachment member 106 of thepreceding paragraph. The frame 180 can be set in from the rear of thetrailer box 120 thereby allowing the apparatus 102 to partially orsubstantially fit underneath the trailer box 120.

The trailer 101 can further include trailer skirts 190R, 190L, 192R,192L that further streamline the trailer 101. The trailer skirt 192L canbe rotatably mounted to the trailer about hinge-line 194 (see FIG. 76).When the apparatus 102 is swung to the side of the trailer 101 asillustrated at FIG. 85, the trailer skirt 192L can fold out of the way(see FIGS. 86 and 87).

In certain embodiments, the exterior cover 204 is attached to an adapterfairing 305 placed between the vehicle 201 and the drag reducingapparatus 202. The exterior cover 204 can be attached to the attachmentmember 206, the adapter fairing 305, one or more moveable intermediatemembers 207 ₁₋₅, and/or the moveable end member 208. The exterior cover204 can be sandwiched and clamped between the attachment member 206 anda cover clamp 205. The cover clamp 205 can serve as a mounting bracketfor the adapter fairing 305. The moveable intermediate members 207 ₁₋₅are positioned between the attachment member 206 and the moveable endmember 208. The driving linkage 240 is connected to the attachmentmember 206 and the moveable member 208. The driving linkage 240 is alsoconnected to the moveable intermediate members 207 ₁₋₅.

The moveable members 108, 208, 307, 308 and the attachment members 106,206, 306 can take a variety of shapes conforming to or approximatelyconforming to a shape of the vehicle 101, 201 to which the drag reducingapparatus 102, 103, 105, 202, 302 is attached. For example, FIGS. 4-9,43, and 44 illustrate the attachment member 306, the moveableintermediate members 307 ₁₋₄, and the moveable end member 308 whichconform to the shape of the sports-utility vehicle 201, and FIGS. 72-74illustrate the moveable end member 108 which conforms to the shape ofthe semi-trailer truck 100. In other examples, moveable membersapproximately conform to a shape of an associated vehicle and aredefined by a series of line segments and/or arcs around a perimeter thatapproximately matches the shape of the associated vehicle. Asillustrated at FIGS. 71 and 72, the drag reducing apparatus 105 forms atransition between the shapes of the tractor unit 110 and the trailer101. In such transitional embodiments where multiple moveable membersare used, each successive moveable member could form a part of thetransition. In certain embodiments, illustrated at FIGS. 4 and 47, theattachment member 206 and the moveable end member 208 conform to theshape of the sports-utility vehicle 201, but the moveable intermediatemembers 207 ₁₋₅ only conform to a lower portion of the shape of thesports-utility vehicle 201. In such embodiments, the exterior cover 204is held taut between the attachment member 206 and the moveable endmember 208. The moveable intermediate members 207 ₁₋₅ primarily hold theexterior cover 204 from drooping excessively when the drag reducingapparatus 202 is in the retracted configuration (e.g., to keep theexterior cover 204 from touching or dragging on the ground).

To provide an underlying shape and support for the exterior cover 304that provides a gently sloping aerodynamic surface behind the vehicle201, each moveable intermediate member 307 ₁, 307 ₂, 307 ₃, 307 ₄ issized progressively smaller than the preceding moveable intermediatemember 307 ₁, 307 ₂, 307 ₃ as illustrated at FIGS. 5 and 6. When in theextended configuration, the collective shape of the moveableintermediate members 307 ₁, 307 ₂, 307 ₃, 307 ₄ along with the shape ofthe attachment member 306 and/or the adapter fairing 305 defines theoverall exterior shape of the drag reducing apparatus 302. In certainembodiments, an angle, α, is defined between a horizontal planeapproximately at the top of the vehicle 201 and a top sloping surface ofthe drag reducing apparatus 302 as illustrated at FIG. 2. In certainembodiments the angle, α, varies from zero degrees to about 25 degrees.In a preferred embodiment, the angle, α, is between about 10 and about15 degrees. Likewise, in certain embodiments, an angle, β, is definedbetween a horizontal plane approximately at the underside of the vehicle201 and a bottom sloping surface of the drag reducing apparatus 302 asillustrated at FIG. 2. In certain embodiments the angle, β, varies fromzero degrees to about 25 degrees. In other embodiments, the angle, β, isbetween zero and about 15 degrees, between about 5 degrees and about 15degrees, or between about 10 degrees and about 15 degrees. In certainembodiments, an angle, γ, is defined between a vertical planeapproximately at the side of the vehicle 201 and a side sloping surfaceof the drag reducing apparatus 302 as illustrated at FIG. 3. In certainembodiments the angle, γ, varies from zero degrees to about 25 degrees.In a preferred embodiment, the angle, γ, is between about 10 degrees andabout 15 degrees.

The discussion of the angles α, β, and γ in the preceding paragraph alsoapplies to the exterior cover 204 of the apparatus 202 and to theexterior cover 104 of the apparatuses 102 and 103 (see FIGS. 77 and 78).The apparatus 105 includes angles comparable to the angles α, β, and γof the tail mounted embodiments, and the angles are chosen to blend thevehicle surfaces across the gap G. In the depicted embodiment of FIGS.71 and 72, the semi-trailer 101 is larger (e.g., taller) incross-section than the tractor unit 110, and the angles of the extendedexterior cover result in the apparatus 105 having a down-streamcross-section that is larger than an up-stream cross section.

In certain embodiments, the exterior cover(s) 104, 204 of the fullyextended aerodynamic drag reducing apparatus 102, 103, includepredominantly planar exterior surfaces. In other embodiments, theexterior surfaces of the exterior cover(s) of the fully extendedaerodynamic drag reducing apparatus are non-planar. In still otherembodiments, the exterior surfaces of the exterior cover(s) 204, 304 ofthe fully extended aerodynamic drag reducing apparatus 202, 302 are amixture of both planar and non-planar surfaces. In preferredembodiments, the exterior surface of the exterior cover(s) 104, 204, 304is a developable surface (i.e., a surface with zero Gaussian curvature).Thus the exterior surface can be flattened onto a plane withoutstretching or compressing. Such exterior developable surfaces cantherefore be made of planar material that does not easily stretch orcompress. In preferred embodiments, the exterior cover(s) 104, 204, 304are of constant thickness and are developable from planar materialwithout stretching or compressing the planar material. In otherembodiments, the exterior cover(s) are piecewise developable and can bemade by joining multiple pieces of planar material without stretching orcompressing. In still other embodiments, the exterior cover(s) are notdevelopable but can be made by forming (i.e., stretching and/orcompressing) material into a non-planar and non-developable shape. Inyet other embodiments, the exterior cover(s) are not developable but canbe made by tailoring material into a non-planar shape approximation.

In certain embodiments of the present disclosure, a radiused transitionbetween the vehicle and the drag reducing apparatus can be used. Theradiused transition can be part of an exterior cover of the apparatus,can be included on a faring between the vehicle and the apparatus, orcan be both on an exterior cover and on a faring. Examples of such aradiused transition are disclosed at U.S. Pat. No. 7,380,868, previouslyincorporated by reference.

The moveable members 307 of the embodiment illustrated at FIGS. 5 and 6have a continuous outside perimeter and form a closed, hoop-likestructure. In the embodiment illustrated at FIGS. 71 and 72, themoveable member can be “C” or “U” shaped. In still other embodiments,the moveable frames may be “L” shaped. In general, the shape of themoveable frames are tailored to the specific application and does notneed to form a closed shape nor does it need to completely define across-sectional shape of the aerodynamic drag reducing apparatus (e.g.,the moveable members 207 illustrated at FIG. 47).

Certain embodiments of the present disclosure have pairs of apparatusesthat form right and left halves of a drag reducing shape. Examples ofsuch split apparatuses are disclosed at U.S. Pat. Nos. 7,374,230 and7,380,868, previously incorporated by reference.

In certain embodiments, as illustrated at FIGS. 5 and 6, the firstmoveable member 307 ₁ is supported by the support linkages 311 ₁, 411 ₁which in turn are supported by the attachment member 306. The secondmoveable member 307 ₂ is supported by the support linkages 311 ₂, 411 ₂which in turn are supported by the first moveable member 307 ₁. Thethird moveable member 307 ₃ is supported by the support linkages 311 ₃,411 ₃ which in turn are supported by the second moveable member 307 ₂.

The fourth moveable member 307 ₄ is supported by the support linkages311 ₄, 411 ₄ which in turn are supported by the third moveable frame 307₃ and so on. The quantity of the support linkages 311, 411 may varydepending on the space available, the expected loading at the givenposition, and other reasons. At least two linkages with non-parallelhinge-lines are needed to support a given moveable member 307. Thesupport linkages 311, 411, the moveable members 307 and the attachmentmember 306 support loads imposed on the apparatus by gravity, airflow,uneven roads, and other operational causes.

In certain embodiments, only one moveable member may be supported by oneset of support linkages which, in turn, is supported by an attachmentframe. The exterior covers 104, 204, 304 can be urged inward by elasticelements connected at one end to the linkage 140R, 140L, 240, 311, 340,411 and at an opposite end to the exterior cover 104, 204, 304. When theapparatus 102, 202, 302 is in the extended configuration, the elasticelements are overpowered by the tension in the exterior cover 104, 204,304 which is pulled taut. When the apparatus 102, 202, 302 is retracted,the elastic elements urge portions of the exterior cover 104, 204, 304inward resulting in most of the exterior cover 104, 204, 304 residingwithin the boundaries of the exterior cover 104, 204, 304 when fullyextended. Such elastic elements are further described at U.S. PatentApplication Publication No. 2008/0303310 and illustrated at FIG. 39 ofthis publication, previously incorporated by reference.

In preferred embodiments, as illustrated above, the support linkages311, 411 have two links 413 and 415 a center hinge 322 and two endhinges 321. In other embodiments, more than two links and three hingesmay be used. In still other embodiments, spring elements may besubstituted for one or more of the hinges 321, 322. The hinges 321, 322can have rotatable elements or can be a hinge made of flexible material(e.g., a plastic hinge). Joints of the hinges can be cylindrical orspherical.

In certain embodiments, the hinges 321, 322 are spring loaded to biasthe aerodynamic drag reducing apparatus 302 toward the fully extendedconfiguration. As illustrated at FIG. 18 a motor 331 driving a pulley332 reeling a tension-member 333 terminated at an attachment point 334to the end moveable member 307 ₄ is used to overpower the bias andretract the apparatus 302.

In certain embodiments, the linkages are spring loaded to bias theaerodynamic drag reducing apparatus 102, 202, 302 toward the fullyretracted configuration. The partial vacuum present when the vehicle101, 201 exceeds a given speed overpowers the bias and the apparatus102, 202, 302 extends.

In still another embodiment, the exterior cover 104, 204, 304 issufficiently airtight to allow compressed air delivered within theaerodynamic drag reducing apparatus 102, 103, 202, 203, 302 to extendthe apparatus 102, 103, 202, 203, 302. Conversely a partial vacuumwithin the apparatus 102, 103, 202, 203, 302 can be used to retract theapparatus 102, 103, 202, 203, 302.

In certain embodiments of the present disclosure, illustrated at FIGS.1-42, the driving linkage 340 is a scissors linkage 340 _(R), 340 _(S),340 _(C), and the support linkages 311 ₁₋₄ are substantially a mirrorimage of their corresponding support linkage 411 ₁₋₄. As depicted, thescissors linkages 340 _(R), 340 _(S), 340 _(C) provide lateral supportfor side loads applied on the drag reducing apparatus 302, and thesupport linkages 311 ₁₋₄, 411 ₁₋₄ can carry vertical loads applied onthe apparatus 302. In addition, the scissors linkages 340 _(R), 340_(S), 340 _(C) can provide a means for extending the apparatus 302.Certain forms of the scissors linkage 340 _(R), 340 _(S) also provide ameans for retracting the apparatus 302. A first link 345 ₁ of thescissors linkage 340 _(R), 340 _(S), 340 _(C) is rotatably connected tothe attachment member 306 at an attachment member mount 350. Thescissors linkage 340 _(R), 340 _(S), 340 _(C) can longitudinallyposition the moveable intermediate members 307 ₁₋₄ of the apparatus 302.Connections for this purpose can be provided at rotational jointsbetween the scissors linkage 340 _(R), 340 _(S), 340 _(C) and a moveableintermediate member mount 352 ₁ on the moveable intermediate member 307₁, a moveable intermediate member mount 352 ₂ on the moveableintermediate member 307 ₂, a moveable intermediate member mount 352 ₃ onthe moveable intermediate member 307 ₃, and a moveable member mount 352₄ on the moveable member 307 ₄. The moveable end member 308 can beattached to the moveable member 307 ₄.

In addition to providing lateral support and longitudinal position tothe apparatus 302, certain forms of the scissors linkage 340 _(R) canalso provide vertical support. In the embodiment illustrated at FIGS.5-24, an actuator 420 includes a guide rail 422, a cam follower 424slidably attached to the guide rail 422, a drive belt 426 that drivesthe cam follower 424, a first pulley 428, a second pulley 430, a motor331, and a pivoting connection 432. The drive belt 426 is preferablyrouted between the first pulley 428 and the second pulley 430. The motor331 is rotatably connected to the first pulley 428 and thereby connectedto the drive belt 426. The motor 331 can therefore raise and lower thecam follower 424. The pivoting connection 432 is mounted on the camfollower 424 and also is rotatably connected to the scissor linkage 340_(R). Running the motor 331 in a first rotational direction thereforeextends the scissor linkage 340 _(R) and thereby extends the apparatus302. Running the motor 331 in a second rotational direction thereforeretracts the scissor linkage 340 _(R) and thereby retracts the apparatus302.

In certain embodiments, a tension-member pulley 332 in cooperation witha tension-member 333 may assist the scissors linkage 340 _(R) in theretraction of the apparatus 302. The tension-member pulley 332 and thefirst pulley 428 may be driven by the same motor 331 or by separatemotors. If driven by the same motor 331, a differential gearbox (e.g., aplanetary gearbox) may rotationally connect to each of the pulleys 332,428 and the motor 331 to variably distribute the torque and speed of themotor 331 to each of the pulleys 332, 428 when retracting the apparatus302. In particular, the rotational speed of the motor 331 can be geareddown, and a torque balance between the motor 331, the tension-memberpulley 332, and the first pulley 428 can be established by the gearing.During retraction of the apparatus 302, the relative rotational speedsbetween the tension-member pulley 332 and the first pulley 428 maychange due to the kinematics of the scissors linkage 340 _(R) and theapparatus 302. The torque balance between the tension-member pulley 332and the first pulley 428 is maintained during the retraction of theapparatus 302 even though the relative rotational speeds between thetension-member pulley 332 and the first pulley 428 change. This allowsboth the tension-member 333 and the scissors linkage 340 _(R) tocontinuously contribute to the retraction of the apparatus 302 duringthe retraction of the apparatus 302 powered by the same motor 331.

As mentioned above, the scissors linkage 340 _(R) can also providevertical support to the apparatus 302. The support can be provided atthe rotational joints between the scissors linkage 340 _(R) and themoveable intermediate member mount 352 ₁ on the moveable intermediatemember 307 ₁, the moveable intermediate member mount 352 ₂ on themoveable intermediate member 307 ₂, the moveable intermediate membermount 352 ₃ on the moveable intermediate member 307 ₃, and the moveablemember mount 352 ₄ on the moveable member 307 ₄.

If the kinematic path taken by the scissors linkage 340 _(R) is not thesame as the kinematic path taken by the support linkages 311 ₁₋₄, 411₁₋₄, the scissors linkage 340 _(R) can bind with the support linkages311 ₁₋₄, 411 ₁₋₄. In one example, an extension-retraction path of thesupport linkages 311 ₁₋₄, 411 ₁₋₄ is horizontal and linear while anextension-retraction path of a scissors linkage similar to the scissorslinkage 340 _(R) is approximately horizontal but is not linear. Sincethe extension-retraction paths do not match exactly, binding can occurwhere they deviate from each other. The scissors linkage 340 _(R)resolves this by employing a curved guide rail as the guide rail 422.The curved guide rail matches the kinematics of the scissors linkage 340_(R) and the support linkages 311 ₁₋₄, 411 ₁₋₄. Another solution toprevent binding between the scissors linkage 340 _(R) and the supportlinkages 311 ₁₋₄, 411 ₁₋₄ is to design the linkages 340 _(R), 311 ₁₋₄,411 ₁₋₄ to have matching linear movement and a linear guide rail.

An alternative embodiment of the present disclosure removes the supportlinkages 311 ₁₋₄, 411 ₁₋₄, featured at FIGS. 5 through 24, and supportsthe drag reducing apparatus 302 with the scissors linkage 340 _(R). Thetension-member 333, illustrated at FIGS. 18-24, can assist the scissorslinkage 340 _(R) in the support of the apparatus 302 (with or withoutthe support linkages 311 ₁₋₄, 411 ₁₋₄). In particular, thetension-member 333 can provide a vertical component of support for theapparatus 302. By removing the support linkages 311 ₁₋₄, 411 ₁₋₄, thepotential for them binding with the scissors linkage 340 _(R) is removedand any guide rail can be used as the guide rail 422 without the concernof matching linkage kinematics. In the present alternative embodiment,the moveable intermediate members 307 ₁₋₄, via the moveable intermediatemember mounts 352 ₁₋₄, are rotatably connected to the scissors linkage340 _(R), as previously described. In addition, the moveableintermediate members 307 ₁₋₄ can be connected to the exterior cover 304.The second end of the exterior cover 304 can be clamped between themoveable member 307 ₄ and the moveable end member 308. An additionalconnection, such as a sliding connection, can be added between each ofthe moveable intermediate members 307 ₁₋₄ and a corresponding upperpivot 356 or a corresponding mid-pivot 354 of the scissors linkage 340_(R). Adding the additional connections can stabilize or assist instabilizing the intermediate members 307 ₁₋₄ in the absence of thesupport linkages 311 ₁₋₄, 411 ₁₋₄, especially when the apparatus 302 isnot in the fully extended or the fully retracted configuration.

Yet another alternative embodiment of the present disclosure removes thesupport linkages 311 ₁₋₄, 411 ₁₋₄ and the moveable intermediate members307 ₁₋₃, featured at FIGS. 5-24, and supports rearward portions of thedrag reducing apparatus 302 with the scissors linkage 340 _(R). Thetension-member 333, illustrated at FIGS. 18-24, can assist the scissorslinkage 340 _(R) in the support of the apparatus 302. In the presentalternative embodiment, the scissors linkage 340 _(R) pushes outwardlyon, vertically supports, and laterally supports the last (and only)moveable member 307 ₄ and the second end of the exterior cover 304 pullsagainst the moveable member 307 ₄ when the drag reducing apparatus 302is fully extended. The first end of the exterior cover 304 is attachedto and pulls against the attachment member 306, the fairing 305, and/orthe vehicle 201 when the apparatus 302 is fully extended. Thus, in thefully extended configuration, the compressive loads within the scissorslinkage 340 _(R) are at least partially balanced by the tensile loads ofthe exterior cover 304 resulting in a stable configuration and resultingin the exterior cover 304 being pulled taut. In the fully extendedconfiguration, the tensile loads within the exterior cover 304, thecompressive loads within the scissors linkage 340 _(R), other loads(e.g., bending) within the scissors linkage 340 _(R), and the attachmentmember 306 support the exterior cover 304. When partially or fullyretracted, the scissors linkage 340 _(R) supports the second end (i.e.,a rear end) of the exterior cover 304 via the moveable member 307 ₄, andthe attachment member 306 supports the first end (i.e., a front end) ofthe exterior cover 304. Support straps and rods similar to the moveableintermediate members 207 ₁₋₅ (see FIGS. 47, 49, 51, 54, and 58) can beadded between various points of the scissors linkage 340 _(R) and theexterior cover 304 to keep the exterior cover 304 from reaching theground (e.g., by drooping) when the drag reducing apparatus 302 is notfully extended. The support straps can be stretchable ornon-stretchable. The moveable end member 308 can be attached to themoveable member 307 ₄ and can be attached to the exterior cover 304.

In another embodiment, illustrated at FIGS. 25 through 30, the scissorlinkage 340 _(S) extends and retracts the apparatus 302 by employing ascrew drive including the motor 331, a drive screw 442, a pivoting drivenut 444, an anti-rotation means 446, and a base pivot 448. The basepivot 448 is rotatably connected to the attachment member 306. Thepivoting drive nut 444 is rotatably connected to an upper pivot 445 of asecond link 343 _(IS) of the scissor linkage 340 _(S). An output shaftof the motor 331 is rotationally connected to the drive screw 442, and ahousing of the motor 331 is held from rotating with the output shaft bythe anti-rotation means 446. The drive screw 442 is threadinglyconnected to the pivoting drive nut 444 and rotatably connected to thebase pivot 448. When the motor 331 rotates in a first direction, thedrive screw 442 pushes the pivoting drive nut 444 away from the basepivot 448 thereby retracting the scissor linkage 340 _(S). When themotor 331 rotates in a second direction, the drive screw 442 pulls thepivoting drive nut 444 towards the base pivot 448 thereby extending thescissor linkage 340 _(S).

In still another embodiment, illustrated at FIGS. 31 through 42, stillanother scissors linkage 340 _(C) extends the apparatus 302. In thisembodiment, a tension-member 462 (e.g., a chain, a cable, a belt, arope, a cord, etc.) is routed across pulleys 464 that are rotatablymounted on the scissors linkage 340 _(C). In the depicted embodiment,the pulleys 464 are co-axial with certain of the pivoting joints of thescissors linkage 340 _(C). Also in the depicted embodiment, a first end462 x of the tension-member 462 is attached to an attachment point 476that is kinematically connected to the moveable member 307 ₄, and asecond end 462 y of the tension-member 462 is attached to an attachmentpoint 474 that is connected to a last scissors link 343 ₄. Atension-member drive 460 includes the motor 331, a drive pulley 466, afirst idler pulley 468, a second idler pulley 472, and a tension spring470. The tension member 462 is routed from the first end 462 x to thetension-member drive 460 and further to and through the scissors linkage340 _(C) and the last end 462 y. In the present embodiment, the drivepulley 466 also serves as a support pulley that is vertically spacedabove the scissors linkage 340 _(C). In the present embodiment, thesupport/drive pulley 466 is rotatably mounted to the attachment member306. The tension member 462 thus angles downward from the support/drivepulley 466 to the first end 462 x and the attachment point 476. Tensionwithin the tension-member 462 can provide a vertical component ofsupport for the apparatus 302.

When the motor 331 rotates the drive pulley 466 in a first direction,the tension-member 462 pulls against certain pulleys 464 attached to thejoints of the scissors linkage 340 _(C) drawing them together andthereby extending the scissors linkage 340 _(C) and the apparatus 302.When the motor 331 rotates the drive pulley 466 in a second direction,the tension-member 462 pulls the attachment point 476 inward and therebydirectly retracts the scissors linkage 340 _(C) and the apparatus 302.When the motor 331 is stopped, it can hold the drive pulley 466 fromturning and thereby hold the configuration of the apparatus 302. A brakecan hold or assist in the holding of the drive pulley 466 from turningand thereby hold or assist in the holding of the configuration of theapparatus 302. A braking clamp can clamp and hold the tension member 462and thereby hold the configuration of the apparatus 302.

As the apparatus 302 extends and retracts, a length of thetension-member 462 route through the scissors linkage 340 _(C) and tothe attachment point 476 changes. The first idler pulley 468 and spring470 can compensate for this and allow the length of the tension-member462 route through the scissors linkage 340 _(C) and to the attachmentpoint 476 to vary and concurrently keep adequate tension in thetension-member 462. As an alternative or a supplement to theroute-length compensation provided by the first idler pulley 468 andspring 470, a tension-member with tensile flexibility can be used as thetension-member 468.

The tension-member 462 is routed within the apparatus 302 between thefirst end 462 x and the second end 462 y of the tension-member 462.Along the routing, the tension-member 462 passes over various pulleysincluding the pulleys 464 on the scissors linkage 340 _(C), the drivepulley 466, the first idler pulley 468, and the second idler pulley 472.Various portions of the tension-member 462 can be identified in a givenconfiguration of the apparatus 302. Certain of the various portions ofthe tension-member 462 expand and contract as the apparatus 302 movesbetween the extended and the retracted configurations, and otherportions of the tension-member 462 remain the same or approximately thesame length. A given increment of the tension-member 462 can passbetween the various portions of the tension-member 462 as the apparatusmoves between configurations. In particular, a portion 462 ₀ of thetension-member 462 is defined between the first end 462 x and the drivepulley 466. Similarly, a portion 462 g is defined between the drivepulley 466 and the first idler pulley 468, a portion 462 f is definedbetween the first idler pulley 468 and the second idler pulley 472, aportion 462 e is defined between the second idler pulley 472 and apulley 464 near the bottom of the first link 345 ₁, a portion 462 a isdefined between the pulley 464 near the bottom of the first link 345 ₁and a pulley 464 near the top of the first link 345 ₁, a portion 462 ₁is defined between the pulley 464 near the top of the first link 345 ₁and a pulley 464 near the bottom of the link 345 ₂, a portion 462 b isdefined between the pulley 464 near the bottom of the link 345 ₂ and apulley 464 near the top of the link 345 ₂, a portion 462 ₂ is definedbetween the pulley 464 near the top of the link 345 ₂ and a pulley 464near the bottom of the link 345 ₃, a portion 462 c is defined betweenthe pulley 464 near the bottom of the link 345 ₃ and a pulley 464 nearthe top of the link 345 ₃, a portion 462 ₃ is defined between the pulley464 near the top of the link 345 ₃ and a pulley 464 near the bottom ofthe link 345 ₄, and a portion 462 d is defined between the pulley 464near the bottom of the link 345 ₄ and the second end 462 y of thetension member 462. (See FIGS. 32, 34, 36, 38, 40, and 42.)

When the motor 331 rotates the drive pulley 466, length increments ofthe tension-member 462 are transferred between the portion 462 ₀ and theportions 462 ₁, 462 ₂, and 462 ₃. The portions 462 a, 462 b, 462 c, 462d, and 462 e remain substantially the same length as the motor 331rotates and the apparatus 302 changes configurations. The portions 462 fand 462 g can vary in length to prevent binding between the scissorslinkage 340 _(C) and the support linkages 311 ₁₋₄, 411 ₁₋₄ as theapparatus 302 travels through its range of motion. In particular, whenthe motor 331 rotates the drive pulley 466 in the first direction,length increments of the tension member 462 are transferred from theportions 462 ₁, 462 ₂, and 462 ₃ (via portions 462 g, 462 f, 462 e, 462a, 462 b, and 462 c) to the portion 462 ₀ thereby extending theapparatus 302. When the motor 331 rotates the drive pulley 466 in thesecond direction, length increments of the tension member 462 aretransferred from the portion 462 ₀ (via portions 462 g, 462 f, 462 e,462 a, 462 b, and 462 c) to the portions 462 ₁, 462 ₂, and 462 ₃ therebyretracting the apparatus 302. The apparatus 302 is thus extended andretracted by transferring length increments of the tension-member 462between the portion 462 ₀ of the tension-member 462 running external tothe scissors linkage 340 _(C) and the portions 462 ₁, 462 ₂, and 462 ₃of the tension-member 462 running between the pulleys 464 of thescissors linkage 340 _(C). Length increments of the tension-member 462can also be transferred to and from the portions 462 f and 462 g of thetension-member 462. Length increments of the tension-member 462 can alsobe transferred to and from varying amounts of tension-member 462 wraparound the pulleys 464, 466 (and in certain embodiments pulleys 468,472) as the apparatus 302 extends and retracts.

In alternative embodiments, some or all of the pulleys 464 may not beco-axial with certain of the pivoting joints of the scissors linkage 340_(C), and/or the attachment points 474, 476 can be connected to otherpoints on the scissors linkage 340 _(C).

FIGS. 43 through 46 illustrate a method of constructing the moveablemembers 307 ₁₋₄ and further illustrate the possibility of additionalmoveable members (e.g., moveable member 307 ₅). In particular, incertain embodiments, all of the moveable members 307 ₁₋₅ can be madefrom a single sheet of planar material by nesting them as illustrated atFIGS. 43 and 44. In certain embodiments, the planar material can be ahoneycomb sandwich structure. In other embodiments, the planar materialcan be a composite material. In still other embodiments, the planarmaterial 500 can include a core material 502 sandwiched by skins 504,506. In one embodiment, the core material 502 is lightweight marineplywood and the skins 504, 506 are aluminum sheet. As furtherillustrated at FIGS. 43 through 46, an outer perimeter of the moveablemembers 307 ₁₋₅ can be angled to match the exterior shape of theaerodynamic drag reducing apparatus 302. In yet other embodiments, themoveable members are not planar but can be contoured in three dimensionsfor various reason such as matching the three dimensional contour of avehicle.

In another embodiment of the present disclosure, illustrated at FIGS.47-69, the drag reducing apparatus 202 includes the driving linkage 240that is a scissors linkage 240. As suggested above, the support linkages311 ₁₋₄, 411 ₁₋₄ can be removed from the embodiment with the scissorslinkage 340 _(R). Likewise, the embodiment of FIGS. 47-69 needs nobi-folding support linkages, but rather is depicted using the scissorslinkage 240 to laterally support, vertically support, and longitudinallylocate portions of the apparatus 202 behind the attachment member 206.The scissors linkage 240 also provides means to extend and retract theapparatus 202.

A tension-member 262, in particular a portion 262 ₀ that extends betweenan end 262 x of the tension member 262 and a support pulley 266, canprovide a vertical support component to the scissors linkage 240 (seeFIGS. 51 and 52). The scissors linkage 240 can be rotatably mountedalong axis A9 (see FIGS. 51 and 53) to the attachment member 206 ordirectly to the vehicle 201. By attaching an end 262 x of thetension-member 262 to the scissors linkage 240, a rotational position ofthe scissors linkage 240 about the axis A9 can be maintained and held bythe tension member 262. As tensile loads in the portion 262 ₀ of thetension-member 262 can also apply a horizontal force component thatpulls the scissors linkage 240 toward the retracted configuration, ameans of resisting that horizontal force is included to maintain anextension length of the scissors linkage 240 at a desired extensionlength. In the depicted embodiment, portions 262 ₁, 262 ₂, 262 ₃, 262 ₄,of the tension-member 262 extend between upper axes A11, A13, A15 andlower axes A12, A14, A16 of the scissors linkage 240 and thereby applytensile loads across the scissors linkage 240. The tensile loads appliedby the portions 262 ₁, 262 ₂, 262 ₃, 262 ₄, of the tension-member 262urge the scissors linkage 240 to extend. This urge to extend iscountered and balanced by the tensile load in the portion 262 ₀ of thetension-member 262. A pair of the upper axes A11, A13, A15, A17 and thelower axes A12, A14, A16, A18 can have one portion of the tension-member262 running between them (e.g. axes A11 and A12), two or more portionsof the tension-member 262 running between them (e.g. axes A15 and A16),or no portions of the tension-member 262 running between them (e.g. axesA11 and A18). The portion 262 ₀ of the tension-member 262 is supportedby the support pulley 266 that can be rotatably mounted to theattachment member 206 or to the vehicle 201.

In the embodiment depicted at FIGS. 47-64 and the embodiment depicted atFIGS. 65 and 66, the end 262 x of the tension-member 262 is attached toa harness 276 that is rotatably mounted to the scissors linkage 240 atthe axis A15. Likewise, an end 262 y of the tension-member 262 isattached to a harness 274 that is rotatably mounted to the scissorslinkage 240 at the axis A15. In other embodiments, the harnesses 274,276 can be attached to other axes of the scissors linkage 240 and can beattached to different axes from one another. In still other embodiments,the tension member 262 can be attached to the scissors linkage 240 byother attachment means and/or can be functionally attached to otherlocations on the scissors linkage 240. In yet other embodiments, thetension-member 262 can run in an endless loop with a portion of the loopconnected to the scissors linkage 240. In the present embodiment, thesupport pulley 266 is also a drive pulley 266. The drive pulley 266 canbe rotated about axis A10 (see FIGS. 51 and 53) in a first rotationaldirection or a second rotational direction by a drive system 260. Whenthe drive pulley 266 is rotated in the first rotational direction, thesecond end 262 y of the tension-member 262 is drawn towards the drivepulley 266. When the drive pulley 266 is rotated in the secondrotational direction, the first end 262 x of the tension-member 262 isdrawn towards the drive pulley 266. In other embodiments, a drive pulleycan be separate from the support pulley. In still other embodiments,other actuators can be used to drive the tension-member 262 (e.g., alinear actuator can be attached to a portion of the tension-member 262).The drive pulley 266 can take various forms. For example, if thetension-member 262 is a roller chain, then the drive pulley 266 ispreferably a compatible sprocket. As another example, if thetension-member 262 is a steel or stainless steel cable, the drive pulley266 can be a cable drum with a spiral cable cradle, and the cable can bewrapped several turns around the cable drum to increase friction betweenthe cable and the cable drum (similar to a capstan winch). In theembodiment depicted at FIGS. 60 and 62, the drive pulley 266 is afriction pulley and the tension-member 262 is a drive belt.

To increase friction between the tension-member 262 and the drive pulley266 a set of pinch rollers 270 can be included with the drive system260. The set of pinch rollers 270 illustrated at FIGS. 60 and 62includes three pinch rollers 271 that are rotatably mounted to a firstpinch roller bracket 272 and/or a second pinch roller bracket 273 aboutaxes A30, A31, and A32. The first pinch roller bracket 272 is rotatablyconnected to the second pinch roller bracket 273 about the axis A30. Aturnbuckle 278 can draw the axis A31 toward the axis A32 as the pinchroller brackets 272, 273 relatively rotate about the axis A30. Theturnbuckle 278 can thus draw the three pinch rollers 271 against thedrive pulley 266 with the tension-member 262 in between them. By havingthree or more pinch rollers 271 circumferentially spaced less than 180degrees apart from each other, the set of pinch rollers 270 is radiallyconstrained about the drive pulley 266. Belt guides at the sides of thedrive pulley 266 can also serve to keep the set of pinch rollers 270from axially sliding off of the drive pulley 266. The angular positionof the set of pinch rollers 270 about the axis A10 can vary depending onthe configuration of the apparatus 202. For example, when the apparatus202 is in the fully retracted configuration (see FIGS. 60 and 62) thetensile-member 262 extends from the drive pulley 266 in twosubstantially downward directions and thus orient the set of pinchrollers 270 as shown. As another example, when the apparatus 202 is inthe fully extended configuration (see FIGS. 51 and 53) thetensile-member 262 extends from the drive pulley 266 in a primarilydownward direction (portion 262 f) and a downward-rearward direction(the portion 262 ₀) and thus orients the set of pinch rollers 270 asshown. Other embodiments can use a single pinch roller 271 to increasefriction between the tensile-member 262 and the drive pulley 266. Instill other embodiments, other anti-slip means can be employed betweenthe drive pulley 266 and the tension-member 262. The drive pulley 266can be driven by various means. In the present embodiment, asillustrated at FIG. 67, an output shaft of the motor 331 is rotationallyconnected to a first sprocket 269. The sprocket 269 engages a rollerchain 268 that in turn engages a second sprocket 267. The secondsprocket 267 is rotationally coupled to the drive pulley 266. The motor331 is preferably a reversible motor and can therefore drive the drivepulley 266 in both the first and the second rotational directions.

The scissors linkage 240 of the present embodiment is configured as aladder-type scissors linkage. The axes A11, A12, A13, A14, A15, A16,A17, A18, A19, A21, A22, A23, A24, and A25 each have an associatedcross-member 249 (see FIGS. 68 and 70). The cross-members 249 can addstability and especially lateral stability to the scissors linkage 240(see FIGS. 47, 51, and 53). The cross-members 249 also provide alocation and rotational axes to mount pulleys 264 on the scissorslinkage 240. In particular, link 243 ₁ includes a cross-member 249 ataxis A21; link 243 ₂ includes a cross-member 249 at axis A11; link 245 ₂includes cross-members 249 at axes A12 and A22; link 243 ₃ includescross-members 249 at axes A13, A23, and A16; link 245 ₃ includes across-member 249 at axis A14; link 243 ₄ includes cross-members 249 ataxes A15, A24, and A18; and link 243 ₅ includes cross-members 249 ataxes A17, A25, and A19. The cross-members 249 resemble rungs on aladder. Link portions 248 connect the cross-members 249 and resemblestringers on the ladder (see FIGS. 68 and 70). In the depictedembodiment, the links 243 ₁₋₅, 245 ₁₋₅ are of typically unequal lengths,in other embodiments, the links can be of equal lengths.

Certain of the link portions 248 can be permanently joined (e.g.,welded) to one or more of the cross-members 249. Certain of the linkportions 248 can be rotatably connected to the cross-members 249 ofother links 245, 243. In particular, link 245 ₁ is connected to thecross-member 249 of link 243 ₁ at axis A21 and to the cross-member 249of link 243 ₂ at axis A11; link 243 ₁ is connected to the cross-member249 of link 245 ₂ at axis A12; link 243 ₂ is connected to thecross-member 249 of link 245 ₂ at axis A22 and to the cross-member 249of link 245 ₃ at axis A14; link 245 ₂ is connected to the cross-member249 of link 243 ₃ at axis A13; link 245 ₃ is connected to thecross-member 249 of link 243 ₃ at axis A23 and to the cross-member 249of link 243 ₄ at axis A15; link 245 ₄ is connected to the cross-member249 of link 243 ₃ at axis A16, to the cross-member 249 of link 243 ₄ ataxis A24, and to the cross-member 249 of link 243 ₅ at axis A17; and,link 245 ₅ is connected to the cross-member 249 of link 243 ₄ at axisA18 and to the cross-member 249 of link 243 ₅ at axis A25. One advantageof the scissor linkage 240 connection configuration of the presentembodiment is a wide spacing of the first link 245 ₁ and a generalnarrowing spacing of the links 243, 245 as the scissors linkage 240extends rearward in the fully extended configuration. This generalnarrowing of the link 243, 245 spacing is complementary with the overallshape of the apparatus 202 and provide greater spacing where laterallyinduced moments can be higher. Other embodiments of the presentdisclosure can use other connection configurations for a scissorslinkage.

The rotatable connection (i.e., rotatable joint) between a typicalcross-member 249 and a typical link 243, 245 is illustrated at FIGS.68-70. The cross-member 249 can have a bore at each end that receiveslinkage pins 290 _(H), 290 _(T). The linkage pins 290 _(H), 290 _(T) canbe held in the bores by a threaded rod 292 that extends between thelinkage pins 290 _(H), 290 _(T). The linkage pin 290 _(T) can haveinternal threads that threadingly connect to the threaded rod 292. Thelinkage pin 290 _(H) can have a bore that receives an internal wrenchingnut 293 (i.e., an Allen nut). The internal wrenching nut 293 includesinternal threads that can draw the threaded rod 292 tight and therebysecure both linkage pins 290 _(H), 290 _(T) into their respective bores.The linkage pins 290 _(H), 290 _(T) can be made of any material suitablefor use in a rotating joint. In one embodiment, the linkage pins 290_(H), 290 _(T) are made of hard anodized aluminum shaft that is groundsmooth on its outer diameter. The links 243, 245 can be rotatablymounted about the linkage pins 290 _(H), 290 _(T) at bores included onthe links 243, 245. A bushing or bearing 291 can be inserted into thebores on the links 243, 245. As illustrated at FIG. 70, two bushings 291can be used with one bushing 291 at each end of the bore. Theillustrated bushings 291 also include thrust flanges. A collar (e.g., aclamping collar) can be placed on the linkage pins 290 _(H), 290 _(T) toretain the link 243, 245 on the linkage pin 290 _(H), 290 _(T) (aclamping collar is illustrated at FIG. 53 on axis A13).

A spring or spring element (e.g., a torsion spring, a leaf spring, acoil spring, a detent, a double detent, a spring loaded cam, etc.) canbe included at one or more of the rotatable connections of the scissorslinkage 240. The spring or spring element can bias the scissors linkage240 to extend, retract, or extend in certain configurations and retractin other configuration. FIGS. 68 and 70 illustrate a torsion coil spring294 connected to link 245 ₁ at a first end and the linkage pin 290 _(H)at a second end. In particular, the first end of the spring 294 is heldby a spring holder 295 to the link 245 ₁, and the second end of thespring 294 is held by a slot at the end of the linkage pin 290 _(H). Thesecond end of the spring 294 is secured to the linkage pin 290 _(H) by akeeper 296 that can be threaded into and threadingly retained by thelinkage pin 290 _(H).

The tension-member 262 of the embodiment illustrated at FIGS. 47-64 and67 is routed within the apparatus 202 between the first end 262 x andthe second end 262 y of the tension-member 262. Along the routing, thetension-member 262 passes over various pulleys including the pulleys 264on the scissors linkage 240, the drive pulley 266, an idler pulley 265at axis A28, an idler pulley 265 at axis A29, and an idler pulley 264 ataxis A20 (see FIGS. 51 and 53). Various portions of the tension-member262 can be identified in a given configuration of the apparatus 202.Certain of the various portions of the tension-member 262 expand andcontract as the apparatus 202 moves between the extended and theretracted configurations, and other portions of the tension-member 262remain the same or approximately the same length. A given increment ofthe tension-member 262 can pass between the various portions of thetension-member 262 as the apparatus moves between configurations. Inparticular, a portion 262 ₀ of the tension-member 262 is defined betweenthe first end 262 x and the drive pulley 266. Similarly, a portion 262 fis defined between the drive pulley 266 and the idler pulley 265 at axisA28, a portion 262 e is defined between the idler pulley 265 at axis A28and the idler pulley 265 at axis A29, a portion 262 d is defined betweenthe idler pulley 265 at axis A29 and the idler pulley 264 at axis A20, aportion 262 a is defined between the pulley 264 at axis A20 and a pulley264 at axis A11, a portion 262 ₁ is defined between the pulley 264 ataxis A11 and a pulley 264 at axis A12, a portion 262 b is definedbetween the pulley 264 at axis A12 and a pulley 264 at axis A13, aportion 262 ₂ is defined between the pulley 264 at axis A13 and a pulley264 at axis A14, a portion 262 c is defined between the pulley 264 ataxis A14 and a pulley 264 at axis A15, a portion 262 ₃ is definedbetween the pulley 264 at axis A15 and a pulley 264 at axis A16, and aportion 262 ₄ is defined between the pulley 264 at axis A16 and thesecond end 262 y of the tension member 262 (see FIGS. 48, 50, 52, 55,57, 59, 61, and 63).

The tension-member 262 of the embodiment illustrated at FIGS. 65 and 66is also routed within the apparatus 202 between the first end 262 x andthe second end 262 y of the tension-member 262. The present embodimentof the apparatus 202 does not include the idler pulleys 265 andtherefore the tension member 262 of the present embodiment does notinclude portions 262 e or 262 f. Instead, a portion 262 d is definedbetween the drive pulley 266 at axis A10 and the idler pulley 264 ataxis A20. In other respects, the tension-member 262 routing of thepresent embodiment is the same as the embodiment of FIGS. 47-64 and 67.

In the embodiment illustrated at FIGS. 47-64 and 67, when the motor 331rotates the drive pulley 266, length increments of the tension-member262 are transferred between the portion 262 ₀ and the portions 262 ₁,262 ₂, 262 ₃, and 262 ₄. The portions 262 b, 262 c, and 262 d remainsubstantially the same length as the motor 331 rotates and the apparatus202 changes configurations except near and at the fully retractedconfiguration where the portions 262 b, 262 c, 262 d may press againstneighboring pulleys 264 and/or cross-members 249 as illustrated at FIGS.60 and 61. The portion 262 a changes length as the apparatus 202 changesconfigurations because the axis A20 is spaced from the axis A9 andbecause the portion 262 a contacts the pulley 264 at axis A21 (see FIG.53) in certain configurations (see FIGS. 58-63) but not in others (seeFIGS. 47-57). The portions 262 e and 262 f change lengths when ascissors linkage boost mechanism 280 is active while the apparatus 202changes configurations, as further described hereinafter. In particular,when the motor 331 rotates the drive pulley 266 in the first direction,length increments of the tension member 262 are transferred from theportions 262 ₁, 262 ₂, 262 ₃, and 262 ₄ (via portions 262 f, 262 e, 262d, 262 a, 262 b, and 262 c) to the portion 262 ₀ thereby extending theapparatus 202. When the motor 331 rotates the drive pulley 266 in thesecond direction, length increments of the tension member 262 aretransferred from the portion 262 ₀ (via portions 262 f, 262 e, 262 d,262 a, 262 b, and 262 c) to the portions 262 ₁, 262 ₂, 262 ₃, and 262 ₄thereby retracting the apparatus 202. The apparatus 202 is thus extendedand retracted by transferring length increments of the tension-member262 between the portion 262 ₀ of the tension-member 262 running externalto the scissors linkage 240 and the portions 262 ₁, 262 ₂, 262 ₃, and262 ₄ of the tension-member 262 running between the pulleys 264 of thescissors linkage 240. Length increments of the tension-member 262 canalso be transferred to and from the portions 262 f and 262 e of thetension-member 262. Length increments of the tension-member 262 can alsobe transferred to and from varying amounts of tension-member 262 wraparound the pulleys 264, 265, 266 as the apparatus 202 extends andretracts.

In alternative embodiments, some or all of the pulleys 264 may not beco-axial with certain of the pivoting joints of the scissors linkage240, and/or the attachment harnesses 274, 276 can be connected to otheraxes or points on the scissors linkage 240.

In the embodiment illustrated at FIGS. 65 and 66, there is no scissorslinkage boost mechanism 280, and therefore the portions 262 e and 262 fof the tension member 262 do not exist. In other respects, the presentembodiment transfers length increments in the same way as the embodimentof FIGS. 47-64 and 67.

To obtain a desired configuration of the scissors linkage 240 both whenthe apparatus 202 is fully retracted and fully extended, the transfer oflength increments of the tension member 262 must be balanced. Forexample when retracting, if the portion 262 ₀ of the tension-member 262transfers length increments at a rate higher than portion 262 ₁, 262 ₂,262 ₃, and 262 ₄ can receive, then axis A15 will be drawn up towardsaxis A10 before the scissors linkage 240 is suitably collapsed.Conversely, if the portion 262 ₀ of the tension-member 262 transferslength increments at a rate lower than portion 262 ₁, 262 ₂, 262 ₃, and262 ₄ need, then the scissors linkage 240 will collapse before the axisA15 is suitably drawn towards axis A10. Both the former and the lattercondition will result in a retracted configuration that is not ascompact as a balanced length transfer can achieve. To produce a balancedlength increment transfer, the geometry of the scissors linkage 240, thepositions of the support pulley 266 and the pulley 264 at axis A20, andthe routing of the tension-member 262 through the scissors linkage 240can be compatibly selected. To fine tune the balance of the lengthtransfer, the reference distance Dp (see FIG. 47) locating the pulley264 at axis A20 (see FIG. 51) can be adjusted.

Interaction between the scissors linkage 240, the tension member 262,the pulley 264 at axis A20, and the support pulley 266 defines kinematicmovement of the apparatus 202 as it moves between the fully extendedconfiguration and the fully retracted configuration. In preferredembodiments, the kinematic movement results in a low center-of-gravityof the apparatus 202 when the apparatus 202 is in the fully extendedconfiguration (see FIG. 51) and in the fully retracted configuration(see FIG. 62). In preferred embodiments, the center-of gravity of theapparatus 202 vertically rises and continues to rise as the apparatus202 moves away from the fully extended and the fully retractedconfigurations. The vertical height of the center-of-gravity of theapparatus 202 therefore preferably reaches a maximum when the apparatus202 is at or near a medial position along its range of motion. As anexample, the center-of-gravity of the apparatus 202 is higher as shownat FIG. 56 than it is at FIG. 51 or 62. By having the center-of-gravityincrease in vertical height as the apparatus 202 moves away from thefully extended and retracted configurations, the apparatus 202 is stableat the fully extended and refracted configurations. Gravity therebyurges the apparatus 202 into either the fully extended or the fullyretracted configurations and the apparatus 202 is a bi-stable apparatus.

In embodiments without a motor, the apparatus 202 can be manually movedbetween the extended and the retracted configurations. As the apparatus202 is manually moved from the extended configuration toward theretracted configuration, gravity initially resists the movement as thecenter-of-gravity of the apparatus 202 rises. At a point of bifurcation,gravity assists in the movement toward the retracted configuration.Likewise, as the apparatus 202 is manually moved from the retractedconfiguration toward the extended configuration, gravity initiallyresists the movement as the center-of-gravity of the apparatus 202rises. At the point of bifurcation, gravity assists in the movementtoward the extended configuration.

In certain embodiments, the scissors linkage 240 looses mechanicaladvantage in the fully retracted configuration, and increasing tensionon the portions 262 ₁₋₄ of the tension member 262 has diminishing effectin extending the scissors linkage 240. The boost mechanism 280 resolvesthis by assisting the scissors linkage 240 when initially extending fromthe fully retracted configuration. The boost mechanism 280 can alsocushion the scissors linkage 240 as it is being fully retracted. In thedepicted embodiment, the boost mechanism 280 is driven by thetension-member 262. In other embodiments, a boost mechanism can bedriven independent of the tension-member. Tensile loads in the portions262 f and 262 e of the tension-member 262 urge axis A28 toward axis A29(see FIGS. 51 and 53). In the refracted configuration, this urgingresults in an upward force being applied to one or more boost links 284.The boost links 284 in turn urges one or more boost cams 281 to rotateclockwise about axis A26 as viewed at FIGS. 51, 62, and 64. The boostcams 281 thus engages boost cam followers 282 rotatably mounted on thescissors linkage 240 at axis A11 (see FIGS. 51 and 53). The boostmechanism 280 thus urges the scissors linkage 240 to extend and can beconfigured to have a high mechanical advantage when the portions 262 ₁₋₄of the tension member 262 have low mechanical advantage. The boost cams281 can be limited by a stop and/or the idler pulleys 265 can reach eachother and thus limit movement of the boost cams 281.

In another embodiment of the present disclosure, illustrated at FIGS.71-93, the drag reducing apparatus 102 includes the pair of drivinglinkages 140R and 140L that are scissors linkages 140R and 140L. Thescissors linkages 140R and 140L are rotatably mounted at one end tolinkage mounts 112R and 112L respectively (see FIG. 73). In the depictedembodiment, the linkage mounts 112R, 112L are attached to the attachmentmember 106, and in particular to a bottom member 106B of the attachmentmember 106. In other embodiments, the linkage mounts 112R, 112L can beattached directly to the vehicle 101 or to the frame 180 of the vehicle101. At an opposite end, the scissors linkages 140R, 140L are attachedto the moveable end member 108. In the depicted embodiment, the scissorslinkages 140R, 140L are mirror images of each other and move andotherwise function as a pair. The exterior cover 104 is held taut by thefully extended scissors linkages 140R and 140L and thus defines a dragreducing shape.

Similar to the embodiments described above, a motor 131 is configured toextend the apparatus 102, when rotating in a first direction, andretract the apparatus 102, when rotating in a second direction. Themotor 131 or a brake can also hold the apparatus at a givenconfiguration by not rotating. The motor 131 turns a drivepulley/support pulley 166 via a shaft 165. The shaft 165 is supported mymounts 114M, 114R, and 114L that can be supported by the attachmentmember 106 and in particular by a top member 106T of the attachmentmember 106. The mounts 114M, 114R, and 114L can alternatively beattached directly to the vehicle 101. The shaft 165 turns sprockets 157Aadjacent to right and left members 106R, 106L of the attachment member106. The sprockets engage a roller chain loop 158. The roller chain loop158 engages sprockets 157B that can be rotatably held by the linkagemounts 112R, 112L (see FIG. 73).

There is no continuous tension-member in the embodiment of FIGS. 71-93.Rather, multiple tension-members 162 ₀, 162 ₁, 162 ₂, 162 ₃, 162 ₄, and162 ₅, perform a similar function in conjunction with roller chain loops156, 158, sprockets 153 _(A), 153 _(B), 157A, 157B, and pulleys 155_(A), 155 _(B), 166. In particular, the sprocket 157B turns shaft 154_(E) of drive assembly 147 ₁ of link 145 ₁ (see FIGS. 90 and 93). Theshaft 154 _(E) thus turns sprocket 153 _(B), and 153 _(A) that areconnected together by roller chain loop 156. The sprocket 153 _(A) turnsshaft 154 _(A), and the shaft 154 _(A) turns pulley 155 _(A). Tensionmember 162 ₁ wraps around pulley 155 _(A) of drive assembly 147 ₁ at afirst end and wraps around pulley 155 _(E) of drive assembly 147 ₂ oflink 145 ₂ at a second end. The pulley 155 _(E) of the drive assembly147 ₂ of link 145 ₂ turns shaft 154 _(E) of drive assembly 147 ₂ of link145 ₂. This repeats through drive assemblies 147 ₁₋₅ of links 145 ₁₋₅and ends with tension member 162 ₅ connecting to link 143 ₅. As thetension members 162 ₁₋₅ accumulate and release from their respectivepulleys 155 _(A), 155 _(E) the effect is similar to that of thecontinuous tension member 262 mentioned above.

The sprocket 153 _(A), the shaft 154 _(A), and the pulley 155 _(A)rotate about axis A7 as shown at FIG. 93. The sprocket 153 _(B), theshaft 154 _(B), and the pulley 155 _(E) rotate about axis A8 as shown atFIG. 93. The link 145 includes axis A4 defined by bore 145 _(A), axis A5defined by bore 145 _(M), and axis A6 defined by bore 145 _(B). The link145 supports the drive assembly 147 by rotatably holding axis A7 inalignment with axis A4, and by rotatably holding axis A8 in alignmentwith axis A6. Link 143 defines axes A1, A2, and A3 with axis A2 definedby crank shaft 143 _(M), axis A1 defined by bore 143 _(A), and axis A3defined by bore 143 _(B). The links interconnect to form the scissorslinkages 140L and 140R. The interconnection of scissors linkage 140L isillustrated at FIG. 90.

The scissors linkages 140L and 140R illustrate a scissors linkage withequal length links. Other embodiments of similar scissors linkages canuse unequal length links.

FIGS. 94-96 illustrate an advantage of the configuration of scissorslinkages 140L and 140R. In particular, the scissors linkages 140L and140R can fold flat without interference. This can produce a more compactapparatus 103.

The end panel 108 can include a folding half 108B operated by a linkage116 and thereby fold with respect to end panel half 108A. The scissorslinkage controls the orientation of both end panel halves 108A, 108B.Other embodiments can control the orientation of end panel with jointstops etc.

The various features and components, including the variousextension/retraction methods (and components thereof), of the variousembodiments may be combined in various ways to create new embodiments.

Latches or similar devices may be use to keep the aerodynamic dragreducing apparatus 102, 103, 202, 203, 302 in a given configuration.

In certain embodiments of the present disclosure, certain supportlinkages and/or moveable frames may deform from one configuration to thenext or while transitioning between configurations. This deformationwill cause forces and moments to develop within the apparatus. Theseforces and moments may be employed to keep the apparatus stable in oneor more configurations.

When extended, drag reducing devices in accordance with the presentdisclosure are typically truncated (see FIGS. 1 and 72). In certaintruncated embodiments, the extended lengths of the drag reducing devicesare such that the effects of drag caused by air flow separation at thetruncated ends are minimal. In example embodiments suitable forover-the-road trailers 101, the drag reducing devices may have extendedlengths, L, greater than or equal to 4 feet, or in the range of 4 to 22feet, or in the range of 8-14 feet. Vehicles having smaller heights andwidths could be equipped with proportionally smaller drag reductiondevices. In certain embodiments, the ratio of the extended length, L, ofthe drag reduction device to a reference dimension of the vehicle is atleast 1 to 1. The reference dimension is typically the smaller of thewidth, w, or the height, h, of the rear of the vehicle body. In theembodiment of FIG. 2, the width, w, is the reference dimension since itis smaller than the height, h. In other embodiments, this ratio is atleast 1.5 to 1, or at least 2 to 1, or at least 3 to 1.

In certain embodiments, drag reducing devices in accordance with thepresent disclosure may be automatically extended or retracted. A controlsystem may be used to automatically control extension and retraction. Incertain embodiments, vehicle speed, crosswind speed, and/or othervehicle parameters may be used to automatically controlretraction/extension. For example, a controller may sense vehicle speed,and automatically cause retraction of the drag reducing device if thevehicle speed moves below a given speed value (e.g., 45 miles per hour).In another example, a controller may sense crosswind speed, andautomatically cause refraction if crosswinds exceed a given value (e.g.,25 miles per hour). Wireless (e.g., radio wave) communication may beused to transmit and receive control system communication andinformation.

Retractable drag reducing devices in accordance with the presentdisclosure can have relatively long extended lengths, L, (see FIGS. 2and 77) as compared to refracted lengths (see FIGS. 15, 62, 83, and 95).Certain embodiments have an extended length, L, to retracted lengthratio of at least 6 to 1. Other embodiments have extended length toretracted length ratios of at least 10 to 1 or at least 20 to 1.

While specific angles and lengths have been specified for certainembodiments of the present disclosure, it will be appreciated that thebroad aspects of the present disclosure are not limited to these values.

The use of subscripts in item numbers in this disclosure typicallyimplies a specific member of a group of related items. The use of thesame number without the subscript typically implies a generic member ortypical member of the group of related items. When a numeric oralphabetic range is in a subscript, each of the items within the rangeis typically referred to.

In the present disclosure, the words “a” or “an” are to be taken toinclude both the singular and the plural. Conversely, any references toplural items shall, where appropriate, include the singular.

From the foregoing it will be observed that numerous modifications andvariations can be effectuated without departing from the true spirit andscope of the novel concepts of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentsillustrated is intended or should be inferred.

What is claimed is:
 1. A drag reducing apparatus comprising: a scissorslinkage; and a flexible tension member routed through the scissorslinkage; wherein when the tension member is driven in a first directionthe scissors linkage extends thereby extending the drag reducingapparatus; wherein when the tension member is driven in a seconddirection the scissors linkage retracts thereby retracting the dragreducing apparatus.
 2. The drag reducing apparatus of claim 1, whereinthe flexible tension member is driven by a pulley.
 3. The drag reducingapparatus of claim 1, wherein the flexible tension member does notsupport compressive loads.
 4. The drag reducing apparatus of claim 1,wherein a center of gravity of the scissors linkage is at an elevation,wherein the elevation of the center of gravity of the scissors linkageis at a high elevation when the scissors linkage is at a locationbetween an extended configuration and a retracted configuration, andwherein the elevation of the center of gravity of the scissors linkageis lower than the high elevation when the scissors linkage is at boththe extended configuration and the retracted configuration.
 5. The dragreducing apparatus of claim 1, further comprising an aerodynamic surfacethat is deployed by the scissors linkage when the scissors linkageextends the drag reducing apparatus and is retracted by the scissorslinkage when the scissors linkage retracts the drag reducing apparatus.6. The drag reducing apparatus of claim 5, wherein the aerodynamicsurface is a flexible aerodynamic surface.
 7. The drag reducingapparatus of claim 1, wherein the drag reducing apparatus is adapted tomount behind a vehicle.
 8. A drag reducing apparatus comprising: amounting structure adapted to mount the drag reducing apparatus to avehicle; an extendible and retractable compression arrangement; anextendible and retractable tension arrangement including at least oneflexible tension member; a first connection between the extendible andretractable compression arrangement and the extendible and retractabletension arrangement; a second connection between the extendible andretractable compression arrangement and the mounting structure; and athird connection between the extendible and retractable tensionarrangement and the mounting structure; wherein the first, the second,and the third connections are arranged in a triangle at least when theextendible and retractable compression arrangement and the extendibleand retractable tension arrangement are extended; and wherein the dragreducing apparatus is supported by compression in the extendible andretractable compression arrangement and by tension in the extendible andretractable tension arrangement at least when the extendible andretractable compression arrangement and the extendible and retractabletension arrangement are partially extended.
 9. The drag reducingapparatus of claim 8, wherein the at least one flexible tension memberis routed through the extendible and retractable compression arrangementand wherein tension in the at least one flexible tension member urgesthe extendible and retractable compression arrangement to extend. 10.The drag reducing apparatus of claim 9, wherein the extendible andretractable compression arrangement includes a scissors linkage.
 11. Thedrag reducing apparatus of claim 8, wherein the extendible andretractable compression arrangement includes a scissors linkage.
 12. Thedrag reducing apparatus of claim 8, wherein the first connection is atan end of the drag reducing apparatus at least when the extendible andretractable compression arrangement and the extendible and retractabletension arrangement are extended.
 13. The drag reducing apparatus ofclaim 8, wherein the first connection is between an end of the dragreducing apparatus and the mounting structure at least when theextendible and retractable compression arrangement and the extendibleand retractable tension arrangement are extended.
 14. The drag reducingapparatus of claim 8, wherein the extendible and retractable compressionarrangement extends beyond the first connection away from the mountingstructure at least when the extendible and retractable compressionarrangement and the extendible and retractable tension arrangement areextended.
 15. The drag reducing apparatus of claim 8, further comprisingan exterior cover, wherein the exterior cover is tensioned by theextendible and retractable compression arrangement at least when theextendible and retractable compression arrangement is fully extended.16. A drag reducing apparatus comprising: a drag reducing exterioradapted to reduce drag on a vehicle when the drag reducing apparatus isin an extended configuration and is positioned behind a rear end of avehicle; and a linkage arrangement adapted to configure the dragreducing exterior of the drag reducing apparatus in the extendedconfiguration and also adapted to configure the drag reducing exteriorof the drag reducing apparatus in a retracted configuration, the linkagearrangement positioned below a cargo hold of the vehicle when the dragreducing apparatus is in the retracted configuration.
 17. The dragreducing apparatus of claim 16, wherein at least a portion of thelinkage arrangement is positioned underneath the cargo hold of thevehicle when the drag reducing apparatus is in the retractedconfiguration and configured to allow access to at least one rear doorof the cargo hold of the vehicle.
 18. The drag reducing apparatus ofclaim 16, wherein at least a portion of the linkage arrangement ispositioned underneath the cargo hold of the vehicle and at a side of thevehicle when the drag reducing apparatus is in the retractedconfiguration and configured to allow access to at least one rear doorof the cargo hold of the vehicle.
 19. The drag reducing apparatus ofclaim 16, wherein the linkage arrangement includes a scissors linkage.20. The drag reducing apparatus of claim 16, further comprising aflexible tension member, wherein tension in the flexible tension memberat least partially supports the drag reducing apparatus at least whenthe drag reducing apparatus is in the extended configuration.